Large number of fonts in Powerpoint

I have a large number of fonts I use in Illustrator, Photoshop, etc. I manage them using FontAgent. But certain fonts will not show up in my list in Powerpoint, and I get a message saying that because of the large number of fonts not all fonts will display. How can I make sure I can use a particular font that is not showing up? I tried closing half my fonts in FontAgent, but that did not work.