Error in webservice soap HTTP response 415 content type 'text / xml; charset = UTF-8 'was not the expected type' application / soap + xml; charset = utf-8 '

I'm trying to consume a soap webservice with nusoap in php and I get the following error:

  

ErrorHTTP Error: Unsupported HTTP response status 415 Can not process   the message because the content type 'text / xml; charset = UTF-8 'was not   the expected type 'application / soap + xml; charset = utf-8 '.   (soapclient-> response has contents of the response) HTTP Error:   Unsupported HTTP response status 415 Can not process the message   because the content type 'text / xml; charset = UTF-8 'was not the   expected type 'application / soap + xml; charset = utf-8 '.   (soapclient-> response has contents of the response)

This is my code:

    $user = 'xxxx';
    $password = 'xxxx';
    $wsdl = "miwebservice?wsdl";

    $client = new nusoap_client($wsdl);
    $client->soap_defencoding = 'UTF-8';
    $client->setHeaders('application/soap+xml; charset=UTF-8');

    $err = $client->getError();
    if ($err) { die('Error en Constructor' . $err ); }

    $client->setCredentials($user, $password, 'basic');


    $Params= array(
        'param1'=> $var1,
        'param2'=> $var2,
        'param4'=> $var3,
        'param5'=> $var4,
        'param6'=> $var5,
        'param7'=> $var6
    );
//dd($Params);
    $result = $client->call('funcion', $Params);

    if ($client->fault) {
        echo 'Fallo';
        print_r($result);
    } else {    // Chequea errores
        $err = $client->getError();
        if ($err) {     // Muestra el error
            echo 'Error' . $err ;
        } else {        // Muestra el resultado
            echo 'Resultado';
            print_r ($result);
        }
    }