php soap - send request for multidimensional array - php

Question

First up, I'm trying to send a soap request using PHP SOAP and the XML that the service accepts is as shown below.
<U_MemberReservedTransaction xmlns="http://tempuri.org/">
<UserID>string</UserID>
<password>string</password>
<memberReservedTransactionRequest>
<memberReservedTransactions>
<ReservedType>string</ReservedType>
<Firstname>string</Firstname>
<Surname>string</Surname>
<IcNew>string</IcNew>
</memberReservedTransactions>
<memberReservedTransactions>
<ReservedType>string</ReservedType>
<Firstname>string</Firstname>
<Surname>string</Surname>
<IcNew>string</IcNew>
</memberReservedTransactions>
</memberReservedTransactionRequest>
</U_MemberReservedTransaction>
Just to summarize what the service is expecting, the service is to receive an array of memberReservedTransactions. My SOAP request call looks like below currently.
$client->callService('U_MemberReservedTransaction', array(
'UserID'=>'test1',
'password'=>'password',
'memberReservedTransactionRequest' => array(
'memberReservedTransaction' => array (
array(
'ReservedType'=>'Renew',
'Firstname'=>'',
'Surname'=>'',
'IcNew'=>''
)
)
)
));
As for what i'm expecting in return is a multidimensional array but my concern now is getting my request accepted.
Note : I'm getting a 500 Internal Server Error
Please help :<