Nothing to export

Hi, I'm using the DTS exporter in Maya 7. Whenever I try to export anything, from a character model down to a polygonal sphere, either using dtsUtility or not, I get an error which says "nothing to export". the dmp.dmp files doesn't show any errors, although a file called MayaOpenSourceReport or something is created, which I don't have on this computer so can't post here. Anyone have any ideas about what the problem is? Thanks,

Stephen.