Sorry Ray, I'm using the Server Validations Insert wizard here.
My trigger is the pressing of the submit button, validation type is "Required" as you've stated, then I have to select a Server variable...is the code you've provided above what I insert in the "Code" option in the Choose Variable to Validate wizard window?
I've added that and uploaded it to the page but, relating to a post I'd added whilst you were away (when you couldn't get FTP access because of your location), it's not doing the second validation at all.
The secondary validation, healthscreeningform_476, has been applied to this page on a single field - the "Have you consulted your GP for any health related issues in the the past 3 years?" radio button question and the textarea below it in the GP section in Step 2.
Here's the link to the form again. The validation set up on Step 1 works, but any additional validations don't.