Problem with tags

I’m having a small problem with tags. At the foot of every page, I have a list of 25 tags, using the following code in my theme…

<?php wp_tag_cloud('smallest=14&largest=26&unit=px&number=25&order=RAND'); ?>

The problem I’m having is that the RAND function doesn’t randomize all my tags. It basically just randomizes the first 25 tags I entered into the DB when I first started posting. Hence, if I add a new post, there might be new tags of equal weight, but they would never appear.

Am I doing something wrong?