Nusoap in Code Igniter 1.5.4

[eluser]heriniaina[/eluser]
I have the same error

A PHP Error was encountered
Severity: Notice

Message: Undefined index:

Filename: libraries/Nusoap.php

Line Number: 6497

I use an external SOAP service (not in the same server)

Code:

$this->nusoap_client = new soapclient("http://radiovazogasy.com/wsdl/?wsdl");
    
    if($this->nusoap_client->fault)
    {
        $text = 'Error: '.$this->nusoap_client->fault;
    }
    else
    {
        if ($this->nusoap_client->getError())
        {
            $text = 'Error: '. $this->nusoap_client->getError();
        }
        else
        {
            $param = array('wsid' => "test");
            $row = $this->nusoap_client->call('rvgHandeha', $param);        
            
            var_dump($row);
        }
    }

Anybody can help?
Thanks