Crystal Reports: Need To Add A New Data-Linked Field To Table

I've recently been revising a report we've been using for years in Crystal Reports 9, a Traveler which displays job information from JobBOSS. I have had a little experience in the past with customizing reports, and this time around I've learned a lot, however, one thing I need to do and can't figure out how for the life of me is this:

How on earth can I add a field to the current table which will link to the correct data? The field I need is an extended description memo. I can add a field by editing the .ttx file using Notepad easily enough, and I can get that added field to show up in the Field Explorer by updating the field definition in the Set Datasource Location window, but when I try to use the field in the actual report through JobBOSS, I get this error message every time:

          An error has occurred in the script on this page.
Line   490
Char:  2
Error: Invalid index. (Exception from HRESULT: 0x8002000B
       (DISP_E_BADINDEX))
Code:  0
URL:   file:///N:/Software/JobBOSS/JobBOSS%
       20Server/Reporting/User-Defined/JBReport.vbs

          Do you want to continue running scripts on this page?

I'm assuming this is because JobBOSS has no idea what kind of data this field needs, and that makes sense to me, but how do I make the connection with this new field and the correct data in JobBOSS? I've tried renaming the field everything I could think of in case the connection was being made that way, but nothing works. It seems to me like it should be a simple thing and I am just missing something obvious, but I've spent hours searching for the way to do this and have come up empty-handed.

What am I missing here?