ON F12 in CHUI - not working

I used this code that looks something like below in GUI and CHUI.

But I have a bit confusing when it was working properly in GUI but it was not working in CHUI. Please an assistance for this.

ON F12 of b-tran in frame main-f do:

if lSellByExt then do:

run oesellext.p persistent (as-c-win, this-procedure).

/* returns output in return-oesellext */

end.

apply entry to self.

return no-apply .

end.

Thanks,

Cheppy.