BlackBerry connection on simulater working, not on device

The following code works fine on the simulato开发者_开发知识库r, but when I deploy it to the BlackBerry device I'm not able to connect, am I doing something wrong?

URL = "socket://" + server + ":" + port + ";deviceside=true;apn=internet;tunnelauthusername=;tunnelauthpassword="; 
conn = (StreamConnection) Connector.open(URL);

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Use this on OS5+ : http://www.blackberry.com/developers/docs/5.0.0api/net/rim/device/api/io/transport/package-summary.html

And this if older : http://www.versatilemonkey.com/HttpConnectionFactory.java