IW51 Can not create repair order

Hi All,

I am using IW51 to create a service notification. By selecting "Create In-house Repair Order" from action box I use "RA" as sales document type and when I click on "Notification and Order" save bottom system does not create repair order and gives me an information message as below:

Accrual key 000004 for order accrual is not defined

Message no. V1839

What can cause this problem?

Thanks,

Omid