Downloaded a OVA file and tried to import it into my VMWare Workstation and if something can go wrong - it does.
the ova package name does not match the ovf file inside it
was the error message, after some searching I found out that a OVA is nothing else than a compressed tar file with another ending but includes the OVF and VHD files.
Using 7-zip to look into it I found the name of the OVF and renamed the OVA to the same name - voila - it works :)