Selection of EHP4 technical usages are all greyed out

Good day

We are currently on ERP6.o SPS 6 and would like to upgrade to ERP 6.0 EHP4. Our system has been defined in SMSY in Solman as an ERP 6.0 system. In selection of Main Instances, ECC Server has been selected as relevant.

In mopz, we create a new maintenance transaction, choose the product version as ERP 6.0 and select our systems. On the next screen we choose "Enhancement Package Installation" and then "find download files".

In the next screen we select the product version and target stack. However, all technical usages are greyed out. When I scroll over it it states that Required Main Instances are SAP ECC Server. Why is it not recognizing the ECC Server as main instance as per smsy?

Please assist.

Thanks

Wilhelm