I have experienced some problems with plugins like WP-Polls and WP-ratings.
The problem was located with the AJAX and I discovered that my wp_head() and wp_footer() were not in the right place. I added them but they seem not to work because the extra code that they should generate (javascript functions, etc..) it is not there.
What could be causing this problem? How I could debug that the calls created by the plugins are well set?