$client = new SoapClient("https://www.dwolla.com/api/TestAPI.svc?wsdl");
$params = array(
  'ApiKey' => $apiKey,
  'ApiCode' => $apiCode,
  'Amount' => $amount,
  'Description' => $description,
  'CustomerID' => $customerId
);


try{
$client->__soapCall("RequestPaymentKey", $params);
}catch(Exception $e){
		echo $e;
		echo "ERROR";
}

Fatal error: Uncaught SoapFault exception: [a:DeserializationFailed] The formatter threw an exception while trying to deserialize the message: Error in deserializing body of request message for operation 'RequestPaymentKey'. End element 'Body' from namespace 'http://schemas.xmlsoap.org/soap/envelope/' expected. Found element 'param1' from namespace ''. Line 2, position 158. in /home/swiftbitcoins/purchase_order.php:21 Stack trace: #0 /home/swiftbitcoins/purchase_order.php(21): SoapClient->__soapCall('RequestPaymentK...', Array) #1 {main} thrown in /home/swiftbitcoins/purchase_order.php on line 21 

$apiKey='0AwevY8CPVHiT2wxoxIl';
$apiCode='oDz1XJ1bjbaTk0i5RMcoEq';
$description='Testing CIB Testing';

$amount=123;

$customerId = "812-504-6527";

$client = new SoapClient("https://www.dwolla.com/api/TestAPI.svc?wsdl");
$client->__soapCall("RequestPaymentKey", array($apiKey, $apiCode, $amount, $description, $customerId));

//RequestPaymentKey returns a boolean: true if the request was successfully processed, False or exception otherwise

if($client)
{
     //function executed succesfully
}
else
{
    //it didn't
}

$client = new SoapClient("https://www.dwolla.com/api/API.svc?wsdl");
//Attempt to buy something with dwolla form
	$client->RequestPaymentKey("0Aw5gdfgfdgdfgdfgJjfsjdfsdfsdfsdfsfsfsfsdfgfgdj2NA+r0QUFnTeofqvRPl",
								"oDzdfgdfgdrgdfvsdfwefvtdbyndgsjfgdgfdghjgklgVwga7qbWoL", 
								"1.50",
								"Testing testing testing",
								"812-504-6527");
print_r($client);

var_dump($client->__getFunctions());