Error: Number range for object RESB does not exist

Hi

I'm trying to convert a planned order (to purch requisition) partially via trxn code MD04. Upon saving I get the above error msg. The complete text of msg is as follows. I've maitained the number ranges of all the objects specified in this error msg. Can somebody explain on how to overcome this problem?

Many thanks

BE

Error Msg Text:

Number range for object RESB does not exist

Message no. 61501

Diagnosis

The system cannot create a document for an MRP element if no number

range or interval has been maintained in Customizing of MRP or if t

number range you have maintained is not allowed.

Below is a list of MRP elements that are affected:

Number range object MRP element

PLAF planned order (operative oder simulative)

EBAN purchase requisition

RESB dependent requirements

MDSM simulative dependent reqmts (long-term plannin

MDTB MRP list

Procedure

Check the number ranges in Customizing. If you do not have the necessa

authorization, please get in touch with your systems administration.