Internal error while creating PM order

Dear all,

I have configured new type of PM order and assinged necessary for general maintenance orders as standard. While I am creating the order every thing is going fine untile save, While saving the order the below error is showing. Could any body help out pls.

Internal error for SAPLPS_RPSCO_S PS_READ_ACPOS JLSP

Message no. BE899

Diagnosis

An internal error has occurred.

System Response

Processing stopped.

Regards

Srinivas