creating online registration form. Submit button won't invoke validation

Hi all

I'm a beginner who is studying an online course and I'm not getting much help from my tutor. I've been asked to create an online application form and i'm struggling with the last part. Creating a submit button which when pressed will submit the form, however this must invoke the validation. When I click submit the reply page just says 'hmmm.... cannot reach this page'. Can you tell me what I'm doing wrong? I've attached the submit button section of the code below.

best wishes

dan