Anemones move around and don't open when they are unhappy. If the anemone is healthy looking other than the fact that it doesn't open, I would put it on a rock that you would like it to attach to and spot feed it. This may take some patience. My anemone took about 3 weeks to attach and then attached to a big rock right smack dab in the middle of my tank. I was so upseet because I had put that rock there to grow zoos on. Oh well, the anemone is happy.

If the anemone starts to shrivel up or is deteriorating then it will be time to worry. Good luck and keep us posted.
Deb
