problem after saving the billing document

HELLO SD GURUS

WHEN I SAVE THE BILLING DOUCUMENT (F2)...IT HAS SAVED...BUT ITS NOT GOING TO ACCOUNTS.....IN VFO2 T.CODE WHEN I

RELEASE TO ACCOUNTS IT SHOWING LIKE...ACCOUNT TYPE D IS NOT DEFINED FOR DOCUMENT TYPE RE

WHAT DOES IT MEAN FRIENDS

ANY IDEA PLZ SUGGEST ME....

THANKING YOU

REGARDS

RAM