__soapCall

No matter what method I call I always get the same fault.  falutcode: 
HTTP, faultstring: Not Found.

Here is a sample of the code:

$wsdl = 'some?wsdl';
$client = new SoapClient($wsdl);

$params = array();
$params['String_1'] = '12345';
$params['Integer_2'] = 12345;

try {
    $response = $client->__soapCall('webServiceMethod',$params);
}
catch (SoapFault $fault) {
    trigger_error("Soap Fault: (faultcode: {$fault->faultcode}, 
faultstring: {$fault->faultstring})",E_USER_ERROR);
}

What does HTTP and Not Found mean?