"Set datasession to" it's a form property then change it in method
Why don't change the data sesion before launch your .PRG?

do this:

Take off the "ON KEY LABEL...." remember to clear the on key label of the form putting in the load: ON KEY

In the Event KeyPress of The form add the next code:

LPARAMETERS nKeyCode, nShiftAltCtrl
do case
case nkeyCode=-1
wait window ' ' && F2=-1 do the case for any key u want to catch
thisform.prg() && prg it's a method of the form call it any way
endcase

in the method thisform.prg() add this code:
SET DATASESSION TO (l_nvariable)
DO junkprg

it's going to work very well.....

Gerardo