[Zope] webdav: collection does not work when I use file type object as baseclass

[Robert Rottermann]

Hi there,

I am creating a product that has a folderish and a file type aspect.
I therefore use both ObjectManager and DTMLMethod as its base classes.

When I do that, I can not use Webdav to access folders which contains
instances of my product anymore.
If I get rid of the DTMLMethod as base class things work fine again.

Is such a combination of base classes sensible?  If yes, what must I do to
have webdav working?

thanks for your help.

Robert
www.redcor.ch