Flat file creation

I am using SAP BC version 4.6 on WIN2000. I have seen posts that reference how to create a positional flat file but I am having no success. I am trying to take an SAP idoc and create a fixed length record type file that matches a specific output requirement. I just now want to prove this works by using the example for the EDI appendix A. The example is the FLR example on page 85. My template is exact and that gets created however when I execute a converttostring the result is null in the error string and blanks in the output string. What should be the corresponding record for this template ??? Any help would be very much appreciated.
Pat Sclafani