WebService Transportadora

Boa noite pessoal,

estou tentando fazer a comunicação com um webservice de uma transportadora, utilizando SOAP, mas não está dando certo...

Gostaria da ajuda de vocês, pq não consigo enxergar onde está o erro =/

Arquivo php:

<?php
$client = new SoapClient('http://xxxxx?wsdl');
$options = array('location' => 'xxxxx/CalculoFrete');

$function = 'calculaFrete';

$arguments= array('calculaFrete' => array(

 'cdDivisaoCliente'=>1,
 'cepDestino' =>'xxxx',
 'cepOrigem'=>'xxxx',
 'login'=>'xx@xx.com',
 'nrIdentifClienteDest'=>'xxx',
 'nrIdentifClienteRem'=>'xxx',
 'nrInscricaoEstadualDestinatario'=>'',
 'nrInscricaoEstadualRemetente'=>'xxxx',
 'psReal'=>'30',
 'senha'=>'',
 'tpFrete'=>'F',
 'tpPessoaDestinatario'=>'F',
 'tpPessoaRemetente'=>'J',
 'tpServico'=>'RNC',
 'tpSituacaoTributariaDestinatario'=>'',
 'tpSituacaoTributariaRemetente'=>'ME',
 'vlMercadoria' =>'60000'

));

	print_r($arguments);
 echo '<pre>';

try{

 $result = $client->__soapCall($function, $arguments, $options);
 echo 'Response: ';
 print_r($result);

} catch (Exception $ex) {

 print_r($ex);
 $client->__getLastRequest();
}
?>

e uma parte do wsdl com a estrutura

<xsd:complexType name="CotacaoWebService">
<xsd:sequence>
<xsd:element minOccurs="0" name="cdDivisaoCliente" nillable="true" type="xsd:long"/>
<xsd:element minOccurs="0" name="cepDestino" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="cepOrigem" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="login" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="nrIdentifClienteDest" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="nrIdentifClienteRem" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="nrInscricaoEstadualDestinatario" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="nrInscricaoEstadualRemetente" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="psReal" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="senha" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpFrete" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpPessoaDestinatario" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpPessoaRemetente" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpServico" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpSituacaoTributariaDestinatario" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="tpSituacaoTributariaRemetente" nillable="true" type="xsd:string"/>
<xsd:element minOccurs="0" name="vlMercadoria" nillable="true" type="xsd:string"/>

</xsd:sequence>
</xsd:complexType>
</xsd:schema>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" attributeFormDefault="qualified" elementFormDefault="qualified" targetNamespace="http://xxx.com">
<xsd:element name="calculaFrete">
<xsd:complexType>
<xsd:sequence>
<xsd:element maxOccurs="1" minOccurs="1" name="in0" nillable="true" type="ns1:CotacaoWebService"/>

</xsd:sequence>
</xsd:complexType>
</xsd:element>

e a mensagem que é retornada na linha em que é feita a chamada: **[message:protected] => Fault: java.lang.NullPointerException**