Prorate Maryland pension exclusion in a part-year return

I am preparing a Maryland part-year return (the other state is Florida, so there is not a second part-year return).  The state instructions say to prorate the amount on line 5 of “PENSION EXCLUSION COMPUTATION WORKSHEET (13A)” based on the number of months of Maryland residence.  TT is not calculating the prorated amount and I do not seem to be able to enter the prorated amount in either that worksheet or on line 10a of Form 502.