Neither validating webform fields nor sending content to email address

Hi,

Webform Associate is a great module! ...so thanks a lot for this ruby! :)

After installing and associating this module with a content type, I've created a node consisting of a body text and webform fields - listed below.
Now the problem is when I click on "submit" the page is reloaded but the webform does neither validate the form (all fields are set to "mandatory") nor send the content to the predefined email address if all fields are filled out correctly.
Before installing this module I never had problems with Webform.module.

I use Drupal 6.10 with Webform 2.6.

I created the following fields:
First name - textfield
Last name - textfield
Email - email
Message - textarea

Would be really great if someone could help me out.

Please let me know if you need more information.
Thanks in advance.

Stefan