Question: A problem in dsolve

I have a problem with dsolve that is explained bellow:

In Maple 14, I get the following result
restart:
eqts:=diff(u(x),x$2)=-M(x)/EI;
                     d  / d      \     M(x)
                    --- |--- u(x)| = - ----
                     dx \ dx     /      EI 
cnds:=u(0)=0,u(l)=0;
                       u(0) = 0, u(l) = 0
M:=x->piecewise(x<=l/2,P/2*x,-P*(x-l)/2);
              /     1    1        1          \
x -> piecewise|x <= - l, - P x, - - P (x - l)|
              \     2    2        2          /
dsolve({eqts,cnds},u(x)):assign(%):u(x):=simplify(u(x));
                                       /                /
                                       |                |
uApplyFunction(x):={Typesetting:-mtable|Typesetting:-mtr|
                                       \                \

                  /                    /                /
                  |                    |                |
  Typesetting:-mtd|{Typesetting:-mtable|Typesetting:-mtr|
                  \                    \                \

                  /            /   3      2      3\  
                  |       1  P \4 x  - 3 l  x - l /  
  Typesetting:-mtd|uminus0-- ----------------------, 
                  \       48           EI            

  rowalign = "", columnalign = "", groupalign = "", 

                                 \                         
                                 |                         
  rowspan = "1", columnspan = "1"|, Typesetting:-mtd(lle0, 
                                 /                         

  rowalign = "", columnalign = "", groupalign = "", 

  rowspan = "1", columnspan = "1"), rowalign = "", 

                                   \                  /
                                   |                  |
  columnalign = "", groupalign = ""|, Typesetting:-mtr|
                                   /                  \

                  /              /   2      2\                 
                  |       1  P x \4 x  - 3 l /                 
  Typesetting:-mtd|uminus0-- -----------------, rowalign = "", 
                  \       48        EI                         

  columnalign = "", groupalign = "", rowspan = "1", 

                  \                                       
                  |                                       
  columnspan = "1"|, Typesetting:-mtd(0<l, rowalign = "", 
                  /                                       

  columnalign = "", groupalign = "", rowspan = "1", 

  columnspan = "1"), rowalign = "", columnalign = "", 

                 \                                         
                 |                                         
  groupalign = ""|, align = "axis", rowalign = "baseline", 
                 /                                         

  columnalign = "center", groupalign = "{left}", 

  alignmentscope = "true", columnwidth = "auto", width = "auto", 

  rowspacing = "1.0ex", columnspacing = "2em", rowlines = "none", 

  columnlines = "none", frame = "none", 

  framespacing = "0.4em 0.5ex", equalrows = "false", 

  equalcolumns = "false", displaystyle = "false", side = "right", 

                           \                                   
                           |                                   
  minlabelspacing = "0.8em"|, rowalign = "", columnalign = "", 
                           /                                   

                                                  \  
                                                  |  
  groupalign = "", rowspan = "1", columnspan = "1"|, 
                                                  /  

                  /   1                                     
  Typesetting:-mtd|xle- l, rowalign = "", columnalign = "", 
                  \   2                                     

                                                  \  
  groupalign = "", rowspan = "1", columnspan = "1"|, 
                                                  /  

                                                  \  
                                                  |  
  rowalign = "", columnalign = "", groupalign = ""|, 
                                                  /  

                  /                /                    /
                  |                |                    |
  Typesetting:-mtr|Typesetting:-mtd|{Typesetting:-mtable|
                  \                \                    \

                  /                /       /   2    2         \  
                  |                |1  P x \4 x +9 l  - 12 l x/  
  Typesetting:-mtr|Typesetting:-mtd|-- ------------------------, 
                  \                \48            EI             

  rowalign = "", columnalign = "", groupalign = "", 

                                 \                         
                                 |                         
  rowspan = "1", columnspan = "1"|, Typesetting:-mtd(lle0, 
                                 /                         

  rowalign = "", columnalign = "", groupalign = "", 

  rowspan = "1", columnspan = "1"), rowalign = "", 

                                   \                  /
                                   |                  |
  columnalign = "", groupalign = ""|, Typesetting:-mtr|
                                   /                  \

                  /     /   3    3    2           2\  
                  |1  P \4 x  - l +9 l  x - 12 l x /  
  Typesetting:-mtd|-- ------------------------------, 
                  \48               EI                

  rowalign = "", columnalign = "", groupalign = "", 

                                 \                        
                                 |                        
  rowspan = "1", columnspan = "1"|, Typesetting:-mtd(0<l, 
                                 /                        

  rowalign = "", columnalign = "", groupalign = "", 

  rowspan = "1", columnspan = "1"), rowalign = "", 

                                   \                  
                                   |                  
  columnalign = "", groupalign = ""|, align = "axis", 
                                   /                  

  rowalign = "baseline", columnalign = "center", 

  groupalign = "{left}", alignmentscope = "true", 

  columnwidth = "auto", width = "auto", rowspacing = "1.0ex", 

  columnspacing = "2em", rowlines = "none", columnlines = "none", 

  frame = "none", framespacing = "0.4em 0.5ex", 

  equalrows = "false", equalcolumns = "false", 

  displaystyle = "false", side = "right", 

                           \                                   
                           |                                   
  minlabelspacing = "0.8em"|, rowalign = "", columnalign = "", 
                           /                                   

                                                  \  
                                                  |  
  groupalign = "", rowspan = "1", columnspan = "1"|, 
                                                  /  

                  /1                                       
  Typesetting:-mtd|- l<x, rowalign = "", columnalign = "", 
                  \2                                       

                                                  \  
  groupalign = "", rowspan = "1", columnspan = "1"|, 
                                                  /  

                                                  \  
                                                  |  
  rowalign = "", columnalign = "", groupalign = ""|, 
                                                  /  

  align = "axis", rowalign = "baseline", columnalign = "center", 

  groupalign = "{left}", alignmentscope = "true", 

  columnwidth = "auto", width = "auto", rowspacing = "1.0ex", 

  columnspacing = "2em", rowlines = "none", columnlines = "none", 

  frame = "none", framespacing = "0.4em 0.5ex", 

  equalrows = "false", equalcolumns = "false", 

  displaystyle = "false", side = "right", 

                           \
                           |
  minlabelspacing = "0.8em"|
                           /
Now, in Maple 15, why I cannot get any solution ?
restart:
eqts:=diff(u(x),x$2)=-M(x)/EI;
                     d  / d      \     M(x)
                    --- |--- u(x)| = - ----
                     dx \ dx     /      EI 
cnds:=u(0)=0,u(l)=0;
                       u(0) = 0, u(l) = 0
M:=x->piecewise(x<=l/2,P/2*x,-P*(x-l)/2);
              /     1    1        1          \
x -> piecewise|x <= - l, - P x, - - P (x - l)|
              \     2    2        2          /
dsolve({eqts,cnds},u(x)):assign(%):u(x):=simplify(u(x));
Error, (in dsolve) invalid input: eval expects its 2nd argument, eqns, to be of type {integer, equation, set(equation)}, but received C_val
Error, invalid left hand side in assignment
                              u(x)