Question: Maple's Stubborn Retention of Old Variable Data / Assignments -- WHY ?

Before doing an explore-plot command I had given constant or expression assignments to certain parameters in preliminary statements, e.g.

k = 4* 10^-5 ;

mpg_o = 45;

mpg_ave = mpg_o - k*(m_d /2 );

mpg_mave = mpg_o - k*(m / 2);

Then I did an explore-plot :

Explore(plot(7.28*m*( (1/mpg_mave) - (1/mpg_{ave) ) ,} m=0..200000_), parameters=[md = 150000..200000]);

But this didn't allow me to vary m_d without losing the plot, so I deleted the first 4 assignment statements above and rewrote the Explore-plot command with  mpg_ave and mpg_mave parameters expressed in terms of k and mpg_{o :}

Explore(plot(7.28*m*( (1/(mpg_o - k*m/2 ) - (1/mpg_o - k*m_d/2) ) ), m=0..200000), parameters=[k=1/3000 ..1/2000, mpg_{o = 40..50] ) ;}

On entering the formula, I get the error message :

Error invalid input : Explore expects value for keyword parameter parameters to be of type {NoUserValue, list(name = range(realcons))}, but received [45 = 40..50, 1/2500 = 1/3000 ..1/2000, m_d = 150000..200000]

Since I had deleted these prior assignment values, I can't understand why Maple is retaining them and doing its own work (or outputing error messages) on the basis of the original data . . . .

Now, when I opened a new worksheet and put the above Explore-plot command on it, it all worked out fine.

Seems Maple is not obeying corrections made to assignments to variables.

This is worrying as if it happens inside a large worksheet, can we really start all over again ?

P.S. Why can't we cut and paste to this forum ?

It really makes things awkward typing all a formula.