action attribute in form is ignored

Why when I put this in myForm.aspx

<form id="form1" runat="server" action="queryBuilder.php" myAttribute="yes" >
<input name="a" value="b" />
<button type="submit>ok</submit>
</form>

 it parses to:

<form name="form1" method="post" action="Form.aspx" id="form1" myAttribute="yes">
<input name="a" value="b" />
<button type="submit>ok</submit>
</form>


...