If you had a link I could look to see what the issue is but here are a couple questions and things to check:
- Is the ID for your form named "form" in the HTML?
- Check to see if messages are required, maybe there is some imbalance in parameters
- You should also add the 'type="text/javascript"' attributes where you are getting jQuery from Google
Also, if you're going to use the Google CDN for getting jQuery you may as well use Microsoft's CDN for getting your validation file. Any of these URLs will work:
- http://ajax.microsoft.com/ajax/jquery.validate/1.5.5/jquery.validate.js
- http://ajax.microsoft.com/ajax/jquery.validate/1.5.5/jquery.validate.min.js
- http://ajax.microsoft.com/ajax/jquery.validate/1.5.5/jquery.validate-vsdoc.js