I wanted to add a new BB user to the BES, but when I do a wireless activation it just sits there for 20 minutes or so and say that the server cannot be found, but if I do a wired activation to the BES it activates without any problems I'm able to send/receive e-mail fine.

The users I activated when we first installed the BES worked fine with the wireless activation. Just recently the only way I can do the activation is wired.

Anyone have any ideas why I can do a wired activation, but not a wireless activation???? Any help would be appreciated. Thanks!!!

Check with the carrier and verify that the line is provisioned with the correct type of BlackBerry Data Plan.
It needs to be an ENTERPRISE blackberry data plan... not a PERSONAL blackberry data plan.

I have a ENTERPRISE blackberry data plan. Is there anything else that would prevent the BES to activate wireless? Wired activation works fine.

Could be any number of things.
Read through this:
BlackBerry Search Results

Thanks for the help. I just figured out that my Spam firewall was blocking the messages that were needed to activate the phone...doh!!!!