Hi Emily
That means the Internal of the other company code is not using A1...To find out what is that IO using, just go to the Settlement rule of any IO in that company and then GO TO > Settlement Parameters
For your case, you need to maintain 32601001 in Alloc Str A1, in the SOURCE section
In the "Settlement" section, either tick the "By Cost Element" or enter a "Settlement cost element"
Br, Ajay M