OCAF: Attribute driver not found

Hi,

I am working with a simple OCAF example I have found on the internet. It adds some data to a document and saves it. This is the code:

TopoDS_Shape aBottle = makeBottle(50, 70, 30);
Handle(AIS_Shape) AISBottle = new AIS_Shape(aBottle);

//Create an application
Application *application= new Application();

//Attach document to application
Handle(TDocStd_Document) document;
application->NewDocument("XmlOcaf",document);

//Get main (root) label
TDF_Label root=document->Main();

//Create child label with tag of your choosing
TDF_Label aLabel=root.FindChild(1,Standard_True);

//Register shape of your choosing with aLabel
TNaming_Builder builder(aLabel);
builder.Generated(aBottle);

//Create new integer attribute on aLabel
Handle(TDataStd_Integer) INT = new TDataStd_Integer();
aLabel.AddAttribute(INT);
INT->Set(3);

application->SaveAs( document, "/home/bbihler/Test.cop");

This works great and if I reload the document, everything is there including the shape.

But when I try to change the format and alter the document creation to:

application->NewDocument("XmlOcaf",document);

then there are errors during saving. It says:

XmlDrivers : Storage Plugin
Variable CSF_XmlOcafResource has not been explicitly defined. Set to /usr/local/share/oce-0.13-dev/src/XmlOcafResource
attention etat fantomatique
attribute driver for type TNaming_UsedShapes not found
attribute driver for type TDocStd_Owner not found
attention etat fantomatique
First step successfull
TDocStd_Application::SaveAs(): The status = 0

The created xml document is so small that it is obviously not correct.
I have googled for the error message "attribute driver not found", but I haven't found anything that helped me solve the issue.

Could you tell me what I have to do to be able to save this data in XML format?

Thank you very much!

Ciao,
Benjamin