Wrath 6 - No Upgrade Possible

It is strange as you don't need to do research for the default defence units. You do need to have a defence facility above a certain level for different, higher researched units. Increase your def fac to match your def HQ and make it 12 or higher. A def hq of 12 and def fac of the same or higher and report back. All of your defence units will then be available that have been researched.

Problem solved, THX