Question:If RootOf appears should there not be more than one solution?

Question:If RootOf appears should there not be more than one solution?

Maple

I am looking at a kinematics function and I have
eq:=-.7260889268e-1*arctanh(.5616816483*tan(.5000000000*sr1)+.8023282641);

If I use
sol1:=solve(eq-eval(eq,sr1=0)-s0,sr1);

I get
sol1=
2.*arctan(RootOf(3630444634*arctanh(5616816483/10000000000*_Z+8023282641/10000000000)-4012053071+50000000000*s0))

but if I use
sol2:=allvalues(solve(eq-eval(eq,sr1=0)-s0,sr1));

I get
sol2=
-2.*arctan(2674427547/1872272161+10000000000/5616816483*tanh(-4012053071/3630444634+25000000000/1815222317*s0))

I then plot sol1 and sol2 for s0=0..-evalf(Pi/2):  sol2 plots for the defined range of s0 but the plot of sol1 has no display when the function is constant.

Questions
I had assumed that if RootOf appears there is more than one solution but is this so?

Physically the plot of sol2 is correct and sol1 is physically correct up to the point at which there is no display. Can anyone help me understand the way in which plot treats these two functions?

I am using Maple10 classic.