SDHC cards for camcorders tend to need to be of a relatively high speed compared to what's acceptable in a still camera.
You'll have to look in your manual for the minimum speed required by your camera, it may be a Class 4 card, it may be Class 6.
Personally, I use 16 gig Class 6 SDHC cards in my camcorder.
A Class 2 card is guaranteed to be too slow for a modern day camcorder. (class 2 tops out at 16Mbit/s - most camcorders that record AVCHD will record 17-24 mbits/s) Class 4 is 32mbit/s, class 6 is 48mbit/s, class 10 is 80mbit/s.