Flash CS5 + Adobe AIR2 class error

As you all know, Flash CS5 is now released. It is confusing me as AIR2.0 is still in beta. so is the air2 in flash cs5 stable or not?

I tried to use DatagramSocket class in Flsh CS5 but failed

import flash.net.DatagramSocket

Up to this point, everythings ok

var ds:DatagramSocket = new Datagramsocket()    

FAILED.VerifyError: Error #1014: Class flash.net::DatagramSocket could not be found.

    at runtime::ContentPlayer/loadInitialContent()
    at runtime::ContentPlayer/playRawContent()
    at runtime::ContentPlayer/playContent()
    at runtime::AppRunner/run()
    at global/runtime::ADLEntry()

I tried replacing the air2 beta 1,air2 beta 2 as stated in the release note but it still fialed..

Any idea anyone?