BOPF: filling ET_FAILED_KEY in determination dumps

Hi,

I created a BOPF model.

I added a determination at 'save'.

In the determination I want to update a standard SAP table (via a standard function module).

Now I want to prevent that the BOPF model is updated if the update of the standard table fails.

So in case the update of the standard table fails I add a message to parameter EO_MESSAGE.  The message is displayed in the test tool but the record is saved in the BOPF model.

I thought parameter ET_FAILED_KEY could prevent that the record is saved in the model. But when I fill the key of the record in ET_FAILED_KEY the system dumps.

Any idea how I can do this?

What is the meaning of parameter ET_FAILED_KEY in a determination?  If I fill it it always dumps!

Thanks for any suggestions!