Problems with SoapClient and local_cert

Hello, I'm trying to connect to a service that requires HTTPS authentication, I follow the steps of PHP manual doing this: $client = new SoapClient("https://IP/wsapis?swdl", array( 'trace' => true, 'local_cert' => 'C:\\myCert.pem', 'passphrase' => 'myPassphrase' )); But I can't access to remote file, when I try to connect I get this error: *PHP* Fatal *error*: Uncaught SoapFault exception: [*WSDL*] SOAP-*ERROR*: *Parsing WSDL*: Couldn't load from 'https://IP/*wsapis?wsdl*' Is necesary to have installed special libraries? Any ideas? Thanks.