ASP.net MVC How to change the Textbox Class upon validation failure?

Question

I notice in the default MVC template project that the Account registration fields are highlighted via a class change.

I can't seem to get the same behavour out of my own code (in the same project - same CSS etc)

What might be stopping this from occuring?

Update

I believe this relates to one of my other questions Because I was having trouble with NullReferenceExceptions I have changed the Html.ValidationMessage fields to have different names than the target fields.

So really, I need to resolve this question

Answer 1

Post some repro code or we can't help. :)

Answer 2

I used jquery to change dinamically the classes of my input controls on error; though it requires to write a lot of code :-S Would you like me to post my solution in here using jquery?