MultiTerm API: External component has thrown an exception.

When attempting the following:

oExpDef.ProcessExport(MtTaskType.mtScript);

I get this error message: External component has thrown an exception.

Resulting .xml file is empty (other than the XML declaration header).

When I change the mtScript to mtWizard, the wizard appears, and without changing any details, the export process works fine.

Does anyone have any ideas on how to solves this error?