Campaign List Export

I'm running into an issue with a campaign list export, I can run the definition fine when I am only extracting columns from the NetContact business object, but if I add any columns from a custom business object the export fails. The workflow process returns a successful status, but the file that is created contains only the text "There was an error creating the query" or similar.

The query itself will run fine in IQA, and the BOD is published. The custom BOD links to NetContact by means of the iMIS ID (not the contact key).

I also discovered that the export will fail if I add a field from a business object that is generated from a standard custom table. Again the source query works fine.

I have also tried creating a new business object which replicates all of the columns in NetContact, and adds in the columns I require from my custom business object, but, no luck there either.

Has anyone come across this before, if so, I'd be very glad to hear how you got around it.