DP90 - Create Billing Request Error

Dear Experts,

I had get an error while create billing request in dp90. Below are the process details:

1. First, I go to IW31 Create Service Order & Service Notification and then complete the Service Order.
2. After that I go to DP90 fill in the Service Order No., then click the 'Billing Request' Button. It appers error 'Material BILL_MAT is not defined for sales org.0800, distr.chan.30,language EN' With Message No is 'V1382'.

I had check in MM02 for the material it had been appeared in sales org 0800 and distr.chan 30. In the additional data ->description tab the description in language 'EN' also had define.

Please help me if you know i miss up any other step.

Regards,

William