Error in KSU5

Hi:

I am facing an error while executing KSU5 in production run, (in test run results were produced without any error). It is saying that GL account xxxx is not defined in XYZ COA ( Message no. F5507 ) . Now i am confused where will this account has to be assigned and from where it was picked by system while posting actual run. Please guide me. Setting are in place in OK17.

Br