Got it too! You have to be in the site with the AgentPress theme activated to activate the plug-in. Hope this helps somebody else!
What did you find out with this problem? I am having the same issue. I have the Genesis Framework installed and the AgentPress Child Theme also installed. Why is it not finding it?
http://www.nancymuslin.melodyslist.com
Installing it on a Multisite and trying to Network Activate.
