The problem had to do with authentication and access-rights to the qvw and the problem with NTLM not supporting Mulit-hop.
The problem appears in a setup where:
SharePoint is installed on Server A
and the Qlikview environment is installed on Server B.
Allowing anonymous-session ussing a session CAL made the qvw available in the Qlikview Object Selector.
Another solution to this setup should be to use Kerberos and configure it to use allow delegation.