Problem with delta update on customised export data source.

Question

Hi all BW gurus,
I have created several customised export data sources in the R/3 system. And I have made use of the utility program <Z_CHANGE_DELTA_PROCESS> to update the ROOSOURCE table.
While this can result in being able to do initial update (instead of full update), the subsuquent delta update is not working.
In RSA7, the datasource is with green light and in RSA3, the extractor can extractor data out of it.
Does anybody have some idea on this?
I heard that there is a way to change the Business Transaction Event (BTE), but I don't quite understand how this is performed. And wonder if this is the only way out. To me, the triggering point would be the same, meaning the InfoPackage would be executed, then call the extractors in R/3 to extract the delta update in order to load into the InfoCube.
And how do others do for executing delta update of the customised data source?
Thanks a lot!!
The utility program of <Z_CHANGE_DELTA_PROCESS>:
=================================================
report z_change_delta_process .
*P_DATAS DataSource
*P_DELTAP Delta Process for DataSource
parameters:
  p_datas type roosource-oltpsource,
  p_deltap type roosource-delta.
tables:
  roosource.
data:
  ls_roosource type roosource.
  if p_datas(2) ne 'Z_'.
   message 'The DataSource needs to begin with ''Z_''.'  type 'E'.
  endif.
select single * from roosource into ls_roosource
       where oltpsource = p_datas
       and objvers = 'A'.
if sy-subrc eq 0.
   ls_roosource-delta = p_deltap.
   update roosource from ls_roosource.
message 'The DataSource has been updated successfully.' type 'I'.
else.
   message 'The DataSource entered is not valid, try again.' type 'E'.
endif.

Answer 1

Doesn't anyone have any idea on this topic?
Appreciate for all the help. Thanks.