jQuery Form Validation plugin - works GREAT but not on SELECT menu

JavaScript
1

I’m using the standard jQuery form validation plugin and it works great on my form inputs but not the select menu. I’ve copied the code from the documentation examples exactly.

<script type="text/javascript" src="http://dev.jquery.com/view/trunk/plugins/validate/jquery.validate.js"></script>
<script  type="text/javascript">

$(document).ready(function(){
	$("#signup_form").validate({
        rules: {
            email: {
                required: true,
                email: true
            },
        },
        messages: {
            email: {
                required: "Enter a valid email address.",
                email: "Enter a valid email address."
            }
        }
    });
	
	
	});
</script>


<label for="heard_from">How did you hear about us? <span class="req">*</span></label> 
<select name="heard_from" id="heard_from" title="Please Select Something"   validate="required:true">
<option value="">-- Choose --</option>
<option value="search_engine">Search Engine</option>
<option value="friend_family">Friend or Family</option>
<option value="advertisement">Advertisement</option>
</select>

Has anyone experienced this problem