cancel message in status "system error" - from synchr. RFC call in IP

Hello guys,

from a synchronous RFC call in an integration process where the receiver determination failed

I have now some messages left in the message monitor with status "system error".

How can I cancel them ?

I tried RSXMB_CANCEL_MESSAGES, RSXMB_CANCEL_NOT_REST_MESSAGES but they were not selected.

Also in the runtime workbenche they cannot be canceled.

Thank you for your help

regards

Hans