Customer exits for PB20

Question

Hi all,
My problem is quite strange, because i know how to do something, but it does not work....obviously :-).
Ok, I am using the customer exist pbas0002 for PB20...I want to change the menu from the standard transaction PB20...
the code in the customer exist is this one:
import progr from memory id 'PRGPB20'.
    if progr = 'ZHRGC'.
      loop at screen.
        if screen-name = 'RPAPP-APLNO'.
          screen-input = 0.
          modify screen.
        endif.
      endloop.
      set pf-status 'ADIS' excluding 'PORT' of program 'SAPMP50A'.
    endif.
Quite easy so far....
Somewhere in another program I am calling the transaction PB20 and before calling I am exporting the value 'ZHRGC' into the memory id 'PRGPB20', but the import command inside the customer exit does not get any value....
Does somebody knows what it could be? Is the abap memory cleaned before the import command?
<i>I tried also, instead of using the export/import command the syst-cprog value, but the value does not correspond to the program where I am calling the transaction.</i>
Here is the part where I call the transacton:
export b to memory id 'PRGPB20'.
set parameter id 'APL' field pernr.
call transaction 'PB20'.

Answer 1

I ran across this a while back, I banged my head against the wall for days, because I was stuborn about my variable names,  I finally changed them to match and the problem was fixed.  From then on, I always make them the same, ALWAYS. 
I found this in the help.......
<i>The structure of the fields, structures, and internal tables that youwant to import must correspond to the objects exported to the dataset.Furthermore, the objects must be imported with the same nameswith which they were exported.</i>
Regards,
Rich Heilman