[SOLVED] Curious issue with validation on Internet Explorer

I have a curious issue:
on the same site I have 2 different form, both with the validation "required".
The first form work well.
The second in Internet Explorer (only) submit the form without requiring the mandatory data.
To test the page that include this form, I added the other and the result is still the same: one works and the other (always the same) not! Of course in all other browser all works well...
Rechecking the configuration of each form seems to me to be the same, but maybe I'm missing something ...

If you want to see the settings I can send you a pm with the backend parameter...

Hi fastmax,

Please post a link to the form so I can take a quick look.

Bob

Hi Bob, being a page of a web marketing campaign, to avoid receiving external visits I write it in a pm

Hi Max,

PM is good.

There's a JavaScript error from the dropdown menu that shows up in IE9

SCRIPT5007: Unable to get value of the property 'getElements': object is null or undefined
dropdown.js, line 87 character 17

But I don't think that is the problem . . .

The form is also inside <p></p> tags - this is illegal HTML and IE chooses to take offence at it. Please see if that switching them to <div></div> tags clears the problem.

Bob

The form is also inside <p></p> tags - this is illegal HTML and IE chooses to take offence at it. Please see if that switching them to <div></div> tags clears the problem.

Bob

BOB, the problem was here!
Now all work well.

Thanks.