Profit center

Hi,

I have created one gl (1001123) and same as created as cost element, for this gl a/c profit center made as reqd field. Now i am posting MIRO, system threws error message like "Field Prof.Segmt is a required field for G/L account 1001123"

If i can remove this field from mandatory to optional then system creates accounting doc as well but if it is mandatory why system threws error? We need to put as mandatory and need to post it...how?

can anybody help on this

thanks

anifi