FoxPro 2.6 - Dos - Date Expiration

one prog in DOS that writen by FoxPro 2.6 work until 12-9-2008 (m/d/y)
but when I try to repair it I can't find the way becuse I search these instruction

mov ah,a2h
int 21h ; Get date

mov ah,4ch
int 21h ; Terminate prog

but this prog don't get date with above Dos Servive

Now I don't know what do I do ? Search for what ?
even after nop all ( 2 times ) terminate code then the prog terminate after
expiration date .

anyone have any Idea ?

other things what Debuger let me to run program in dos insteruction by instruction ?
( Debuger with right version for dos )