BAPI_MATERIAL_SAVEDATA testrun changelog rollback

Hi all,
We use a Z program in our company for material master maintenance.
The creation/extend/update will managed by FM BAPI_MATERIAL_SAVEDATA.
We also provide some kind of test run. So it is possible to collect all errormessages and
display the user. To do this, the FM is called and the changes are reversed using 'BAPI_TRANSACTION_ROLLBACK'.
That works great too. However, it seems that the change documents are not rolled back.
This means that entries in the table CDHDR are written.
Calling from FM MATERIAL_MAINTAIN_DARK in the FM BAPI_MATERIAL_SAVEDATA does not allow to set
flexible the parameters KZ_AEND and KZ_TEST.
How can I prevent this? Does anyone have any ideas?

Thanks in Advance