copy.asmx copyintoitems does not work when source and target is on different servers

Hi,

My problem is getting copy.asmx to copy a file from one MOSS 2007 document library to a WSS3.0 document library (the two libraries are identical).

Using copy.asmx copyintoitems works just fine when source and target is on the same server. If I try to copy onto a different server in a differnt domain I get an eror "object reference not set to an instance of an object". I might this has to do with authentication on the consuming webservice. Any ideas on how to get this right?

Please advice.

Kind regards
Tor Sigve T.