Groove Agent

I have Cubase 8 Pro, using Windows 10 64 bit. I’m trying to access Groove Agent SE. I have watched some videos and looked at forum posts. I go to “add instrument track” but when I’m looking at the pull down list under “No VST Instrument” the only folder showing is “Synth”. No “Drum”, Halion Sonic SE", or “HalionOne” option is available. I can look through the Browse list and find Drum Plugin and far to the right Groove Agent One is visible, but when selecting to add this track, no control window appears and nothing happens when I click on the Edit Instrument button. What am I missing or doing wrong?