Cant consume mendix web service if entity is specialization

Hi all, I'm experimenting with consuming and exposing web services. I have two Mendix projects: one exposes a web service, the other consumes the same web service. The web service has a single operation that retrieves a list of customers from the database. The Customer entity is also a specialization of System.Image. I used the Import Web Service wizard to automatically build out the XML-to-domain mapping and everything, and all the element mappings are accurate. When I tried consuming this web service in the second Mendix project, the web service call doesn't execute right through; it just gives this error popup: An error has occurred while handling the request. However, I've noticed that if I remove the generalization from the Customers entity in the first project, everything works as expected. I don't know why this happens. I've tested this with other generalizations including those in the System module and some that I've created. Can anyone help me figure out what I might be doing wrong here?
1 answers

The release notes of MX 6.5 mention something that could be related:

Fixed conversion issue for 'call webservice' action where the body parameter is inheritance element.

The update from Mx5.20 to Mx6 is not that big, except when you use a lot of custom widgets (Mx6 is stricter in checking widget structure). So maybe you could try if Mx6.5.1 fixes your problem?