For some reason I can't enforce selecting from the "seminar" field

**TAKEN FROM JAVASCRIPT KIT

HTML Code:
/*
Check required form elements script-
By JavaScript Kit (http://javascriptkit.com)
Over 200+ free scripts here!
*/

function checkrequired(which){
var pass=true
if (document.images){
for (i=0;i<which.length;i++){
var tempobj=which.elements[i]
if (tempobj.name.substring(0,8)=="required"){
if (((tempobj.type=="text"||tempobj.type=="textarea")&&tempobj.value=='')||(tempobj.type.toString().charAt(0)=="s"&&tempobj.selectedIndex==-1)){
pass=false
break
}
}
}
}
if (!pass){
alert("One or more of the required elements are not completed. Please complete them, then submit again!")
return false
}
else
return true
}
HTML Code:
<form name="seminarRegister" method="post" action="***" onSubmit="return checkrequired(this)">

<table>
	<tr>
		<td colspan="2" align="center"><strong>Seminar Registration Form</strong></td>
	</tr>
	<tr>
		<td>First Name:</td><td><input type="text" name="requiredfirstName" /> *</td>
	</tr>

	<tr>
		<td>Last Name:</td><td><input type="text" name="requiredlastName" />
		*</td>
	</tr>
	<tr>
		<td>Title:</td><td><input type="text" name="title" /></td>
	</tr>

	<tr>
		<td>Company / Facility Name:</td><td><input type="text" name="company" /></td>
	</tr>
	<tr>
		<td>Mailing Address:</td><td><input type="text" name="requiredaddress" />
		*</td>
	</tr>

	<tr>
		<td>City:</td><td><input type="text" name="requiredcity" />
		*</td>
	</tr>
	<tr>
		<td>State:</td><td><select name="requiredstate">
		<option value=""></option>

<option value="AL">AL</option><option value="AK">AK</option><option value="AZ">AZ</option><option value="AR">AR</option><option value="CA">CA</option><option value="CO">CO</option><option value="CT">CT</option><option value="DE">DE</option><option value="DC">DC</option><option value="FL">FL</option><option value="GA">GA</option><option value="HI">HI</option><option value="ID">ID</option><option value="IL">IL</option><option value="IN">IN</option><option value="IA">IA</option><option value="KS">KS</option><option value="KY">KY</option><option value="LA">LA</option><option value="ME">ME</option><option value="MD">MD</option><option value="MA">MA</option><option value="MI">MI</option><option value="MN">MN</option><option value="MS">MS</option><option value="MO">MO</option><option value="MT">MT</option><option value="NE">NE</option><option value="NV">NV</option><option value="NH">NH</option><option value="NJ">NJ</option><option value="NM">NM</option><option value="NY">NY</option><option value="NC">NC</option><option value="ND">ND</option><option value="OH">OH</option><option value="OK">OK</option><option value="OR">OR</option><option value="PA">PA</option><option value="RI">RI</option><option value="SC">SC</option><option value="SD">SD</option><option value="TN">TN</option><option value="TX">TX</option><option value="UT">UT</option><option value="VT">VT</option><option value="VA">VA</option><option value="WA">WA</option><option value="WV">WV</option><option value="WI">WI</option><option value="WY">WY</option></select>

		*</td>
	</tr>
	<tr>
		<td>Zip:</td><td><input type="text" name="requiredzip" size="9" />
		*</td>
	</tr>
	<tr>

		<td>Email:</td><td><input id="email" type="text" name="requiredemail" />
		*  </td>
	</tr>
	<tr>
		<td>Phone:</td><td><input type="text" name="requiredphone" />
		* (xxx-xxx-xxxx)</td>
	</tr>

	<tr>
		<td>Fax:</td><td><input type="text" name="fax" /></td>
	</tr>
	
	<tr>
		<td>Select the specific seminar:</td><td><select name="requiredseminar" id="seminar">
<option value="">-Choose One-</option>
<!-- EXAMPLES -->
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select></td>
	</tr>
	<tr>

		<td>Indicate Payment Method:</td><td><input type="checkbox" name="payment[]" value="Check" /> Check <input type="checkbox" value="Credit Card" name="payment[]" /> Credit Card <input type="checkbox" name="payment[]" value="Purchase Order" /> Purchase Order <input  type="checkbox" name="payment[]" value="" /> Other</td>
	</tr>
	<tr>
		<td>If "Other" please specify:</td><td><input type="text" name="payment[]" value="" /></td>

	</tr>
	<tr>
		<td>Payment Details:</td><td><input type="text" name="payment_details" value="" /></td>
	</tr>
	<tr>
		<td>Comments:</td><td><textarea name="comments"></textarea></td>
	</tr>

	<tr>
		<td>&nbsp;</td><td><input type="checkbox" name="newsletter" checked="checked" value="1" /> Yes, please sign me up for your <strong>free</strong> newsletter.</td>
	</tr>
	<tr>
		<td>&nbsp;</td><td><input type="submit" name="register" value="Register" /></td>
	</tr>

</table>
I appreciate any help.