Hi
Have you set up the BCA clearing accounts number in the "external payment" node withinIMG path Make Basis Setting for Payment process (the last node) with the relevant external Transaction type?
Honestly I have never configured this object, but I suspect this might be the configuration path that you tell the system to indicate BCA clearing account once F111 is completed.
Please try this to see if this works as you explained
Cheers
taro