Could not submit expense report

Hi All,

      I want map the expense report  to the project and the sales order.(Sales order item type as Expense: Time and Material (Project)  PXAT only the service added in the sales order)

issue: In the WoC: Travel and Expense-->Expense report (selection of the expense report id)  Edit

I can able to add the project and the sales order , but not the Sales Order Item, could not found the sales order item in the select option, without the sales order item I could not submit the expense report.

Please advise , Is there any steps to be followed mandatorily .

Thanks

Vijay