standard troubleshooting steps:
- Check your version of jquery - must be greater than 1.4. Some plugins and themes overwrite this with their own version. Versions of WordPress before 3.0 have an older version of jquery.
Disabe all other plugins and check it again
- The problem can sometimes be certain themes - switch to default WP theme and check it again
- If you report an issue here, please post a url where we can see the problem to have a better chance of getting a response. Also post results of above steps.