warming up an old theme:
Most BAPI functions can not be testet in SM37 because they need a subsequent call of BAPI_TRANSACTION_COMMIT.
I remember having tried to create a test sequence including test BAPI and COMMIT BAPI but I did not succeed.
Right now, I can't find help on that subject.
Please answer to this thread if you have successfully used Function Builder test environment to run a sequence of function calls (in one LUW).
If this is possible, I'm happy to reward you!