After filling form with Watin the submit button remains disabled

Question

I reask this question because no one could give a answer yet and the problem still remains. After filling a form the submit button remains disabled and I don't know how I can fix it. When I click with my mouse into one inputfield the disabled attribute of the Submit button disappears and it is clickable. I couldn't simulate this mouseclick by the Click() Method for this input field.

This is what I've tried yet:

browser.TextField(Find.ById("pvpnet-account-email")).Click();
browser.TextField(Find.ById("pvpnet-account-email")).Focus();
browser.TextField(Find.ById("pvpnet-account-email")).Select();
browser.TextField(Find.ById("pvpnet-account-email")).KeyDown();
browser.TextField(Find.ById("pvpnet-account-email")).KeyUp();
browser.TextField(Find.ById("pvpnet-account-email")).Change();
browser.TextField(Find.ById("pvpnet-account-email")).Blur();

How can I fix it ?