Hi Jamie,
Our current version of DataGraph is validated using standard datasets from NIST. A few years ago (~ version 4.2), we harmonized some of the regression output parameters to be more consistent with terminology from other standard statistical packages. For example, the goodness of fit parameter RMSE is something we did not have in our output in older versions.
It is hard to say exactly what might be the issue with your file. If you could share the file with us (Find our help email under the Help menu in DataGraph) we could take a look to see what might be the issue.