Help with Soap Client

Hi All,

I am using the following code to build a SoapClient with some web service:

////////////////
<?php

ini_set("soap.wsdl_cache_enabled", "0");
ini_set('default_socket_timeout', 600);
$client = new SoapClient("http://iaspub.epa.gov/webservices/StationService/index.html?WSDL",array('trace'
=> 1));
try {
 $sc = $client->getStationCount(43.1,43.5,-83.5,-83.1);
 print $sc;
} catch (SoapFault $exception) {
    echo $exception;
}

?>
//////////////

But I got the following error:
///////////////
Fatal error: Uncaught SoapFault exception: [WSDL] SOAP-ERROR: Parsing
WSDL: Unspecified encodingStyle in /var/www/myphp/wqxststest.php:5
Stack trace: #0 /var/www/myphp/wqxststest.php(5):
SoapClient->SoapClient('http://iaspub.e...', Array) #1 {main} thrown
in /var/www/myphp/wqxststest.php on line 5
///////////////

Also when I tried same code (See below) with another service, it seems
working fine.
///////////////
<?php
$huc = $_REQUEST['huc'];
ini_set("soap.wsdl_cache_enabled", "0");
ini_set('default_socket_timeout', 600);
$client = new SoapClient("http://iaspub.epa.gov/webservices/WatershedSummaryService/index.html?WSDL",array('trace'
=> 1));
try {
 $client->getCharacteristicSummary($huc);
 print $client->__getLastResponse();
} catch (SoapFault $exception) {
    echo $exception;
}
///////////////
?>

I tried to find what's causing this error on Google but no success.
Anyone know what's going on?

Your help is highly appreciated!

Tom