ASP FORM POST Confliting query string acl,policy

I need a little help with a form in ASP .NET C#, it's a standard web application.

The form is used to upload file to Amazon s3 through Cloudfront

<form name="form" action="http://ift.tt/1FF8cdd" method="post" enctype="multipart/form-data">

And inside the form I tryed to use the HTML submit button, but it just reload the page.

<input type="submit" name="submit" value="Upload to Amazon S3" />

So I used a ASP button with PostBackUrl to Cloudfront.

<asp:Button ID="Button1" runat="server" Text="Upload to Amazon" PostBackUrl="http://ift.tt/1FF8cdd" />

When he submit the form the cloudfront xml return an error:

Conflicting query string parameters: acl, policy

I didn't find anything useful on the internet about it.

This same form works just fine in PHP.

Please Help!!!, Cougar