i'm not sure to which SDK you're referring. the latest Flex SDK is 4.6.0, and NetConnection.nearID is present there. the latest AIR SDK is 3.2, and that property should be present there (although i can't test that from where i am right now).
be sure you're targeting at least Flash Player version 10 or above. NetConnection.nearID was not present prior to Flash Player 10.
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