Creating an Incremental Unique Key in Transfer Rules Routine

Question

Hello Experts,
In my Infosource, I have created a routine in the transfer rules on my infoobject.  I am trying to load my data from a flat file and create a unique key by autonumbering a field in my infosource/datatarget. 
I am new to ABAP and can not figure out why my code will not return a value...
Under "Use of Transfer Structure Fields" I chose my field to change only, and entered the following code:
Under Global Code I declared my counter because I want it to maintain its value during the entire load:
  DATA: COUNTER TYPE I VALUE 0.
Then in my routine I have the following code:
  COUNTER = COUNTER + 1.
  RESULT = COUNTER.
  RETURNCODE = 0.
  ABORT = 0.
I expect this to return 1 for the first record, 2 for the second, and so on - therefore giving me a unique key.  Any assistance in my code or other ways to automate this process in BW would be greatly appreciated.
Thank you.

Answer 1

Sean,
It looks like your routine is basically correct.  Have you tried using single quotes around the S instead?  Also - you may want to add a statement to indicate what 0AMOUNT should be in the instance where your condition isn't true.  Something like this:
IF tran_structure-shkzg  = 'S'.
RESULT = tran_structure-wrbtr * -1.
ELSE.
result = ???
ENDIF.
Good luck!  The syntax check in the transfer rules leaves a bit to be desired, doesn't it?