I think that if you are using the release version of Xindice you need to apply a patch to have them work succesfully, look at the email:
http://marc.theaimsgroup.com/?l=xindice-users&m=102521421825423&w=2
After I applied those modifications they worked for me.
(I had to unjar xindice.jar, modify the source code manually, then re-jar it).
Luca
