Hello Bharani and GirishS
I added WWIPurchOrderFormNum field to my Table FreeTextInvoiceHeaderFooterTmp.Extension.
Understanding that you observed the method protected void populateFreeTextInvoiceHeaderFooterTmp(CustInvoiceJour _custInvoiceJour, CompanyInfo _companyInfo) is already receiving a CustInvoiceJour object. I see the suggestion to use _custInvoiceJour.custInvoiceTable().PurchOrderFormNum to obtain the data from the CustInvoiceTable buffer.
To support this I dug into some of the core code (that we don't edit..) and I found the link between 'PurchOrderFormNum' from CustInvoiceTable to CustInvoiceJour: In CustInvoiceJour there is field "PurchaseOrder" with EDT: CustPurchaseOrder and in the Code for CustInoviceJour I see: this.PurchaseOrder = _custInvoiceTable.PurchOrderFormNum;
I tried the steps GirishS mentioned, and used this assignment statement in my WWIFreeTextInvoiceDP_Extension class:
freeTextInvoiceHeaderFooterTmp1.WWIPurchOrderFormNum = _custInvoiceJour.custInvoiceTable().PurchOrderFormNum;
But when I do 'deploy reports' the following errors are reported:
Severity Code Description Project File Line Suppression State
Error An error occurred while deploying the report WWIFreeTextInvoice.Report, WWIFinance.
This might be because the SQL Server Reporting Services has not been installed, or is not configured correctly. 0
Error An error occurred while deploying the report WWIFreeTextInvoice.ReportCopy2, WWIFinance.
This might be because the SQL Server Reporting Services has not been installed, or is not configured correctly. 0
Error The number of defined parameters is not equal to the number of cell definitions in the parameter panel.
at Microsoft.ReportingServices.Library.ReportingService2005Impl.CreateReport(String Report, String Parent, Boolean Overwrite, Byte[] Definition, Property[] Properties, Guid batchId, Warning[]& Warnings)
at Microsoft.ReportingServices.WebServer.ReportingService2005.CreateReport(String Report, String Parent, Boolean Overwrite, Byte[] Definition, Property[] Properties, Warning[]& Warnings) 0
Error An error occurred while deploying the report WWIFreeTextInvoice.ReportCopy1, WWIFinance.
This might be because the SQL Server Reporting Services has not been installed, or is not configured correctly. 0

Looking a little closer at the error messages, I see it's referring to all three designs in the WWIFreeTextInvoice Report. But what I don't get is I didn't edit the report designs?
But I did forget to do a Full Database synchronization. After I ran that.. and my dev system still says "Unable to find the report design WWIFreeTextInvoice.Report."
Frustrating.
I'm not sure how to fix that.
Anyone have any idea of what I might be missing or have messed up?