Billing[release to accounting]

dear all,

i am stuck up with a small problem in billing i.e. after assigning the G/L accounts, i wanted to check weather the release of accounts is taking place or not, so i had a look on billing and clicked on the "release to accounting" then i came acroos an error i.e. "for object RF-BELEG 1990, number range interval 01 does not exist FBN1".

after getting this error i tried to give the number range 01 by using the transaction code FBN1, but i didnt succed in doing so.

can some one help me out by telling what i have to do to solve this problem.

Regards,

sushmitha.