Upgrading ECC 6.0 EHP4 in MOPZ - I'm confused!!!

Okay, I'm totally confused about how the ECC 6.0 EHP4 system should be setup in Solman in order to use MOPZ on it.

I have setup the system as an SAP ERP ENHANCE PACKAGE - ABAP Technology for ERP EHP4, and have used the installed product versions of EHP4 FOR SAP ERP 6.0 / NW7.01 and SAP ERP 6.0, but when I run MOPZ I get to the point where I press the "Find Download Files for the stack version", I keep getting a message that reads "Please assign ERP 6.0 to the Maintenance Optimizer transaction!" When I click on the message it shows me that it's message number if "/TMWFLOW/MO_BACKEND007" but I can't seem to find any information on that.

Any idea what I'm doing wrong?

Thanks in advance!