AgingbyGeneralLedgerAccountDm returns 'null' error

Summary:

We need to upload a custom version of the 'Receivables Aging by General Ledger Account' report. In order to do that we have ran the report front end and are getting data. Downloaded the XML and entered the same parameters + p_coaid into the data model parameters - this is simply to get sample data for the RTF upload. However, we keep getting error 'null', tried all sorts of combinations, different BU etc. Is there any data update required or specific privilege to make this work ? We have not come across this before that sample data cannot be obtained