Anonymous vote is not saved

Hi,

I know there have been some issues reported about this before, but I am still running into this issue. When an anonymous user votes, it shows the vote and says that the vote has been saved. However, after refresh of the node, the user vote disappears (expected behaviour), but the average vote is not updated, so the vote is not counted.

What could be going wrong? Help, I need to go live this weekend with the website!

thanks
ericka