yeast starter problems?

I brewing an Arrogant Bastard clone, so I'm making a starter from a Wyeast pitchable tube, 3 months old.

I have usually made starters (infrequently) in a 22 oz bottle; I'm using a

I used about 1/2 cup DME in ~ 20 oz of boiled water, cooled, added the yeast which was at room temp for 4 hr. I got fermentation within a day, but only bubbles to the surface, not the usual raging top-fermenting thing. The fermentation slowed in 2 days and I figured I didn't give the yeast enough to eat. So I've added ~ 1 cup of DME to about 10 oz of water and boiled it down. I added it, cooled, and I have great "carbonation" but again no raging top fermentation.

Am I not patient enough? I know 3 month old yeast will be rather dormant, but I'm fermenting, just not in the typical way.

Any ideas?

Thanks