This is a Crystal Reports question.  I am trying to add to AR Aged invoice report Average Days to pay from AR Customer Listing With Balance.  I have gone into Crystal Report added to Database Expert AR_CustomerListingBalWrk and linked with AR_AgedInvoiceReportWrk by Sort Field, Group Field, AR Division No and Customer No, then I clicked on  AvgDaysPaymentInvoice:Number and dragged it to the AR aged invoice report. and I get an error code Unable to preview AR_AgedInvoiceReport.RPT.  Invalid index. (Exception from HRESULT: 0x8002000B (DISP_E_BADINDEX)).  Can anyone help?