How to find Connect Wi-ME ?!?

How is it possible to detect a Connect Wi-ME if DIGI DISCOVERY does not detect it ?

I have MAC. May I use them ?

You could possibly take a wireless trace and view by mac address if the device does a discovery, you should be able to see it.
You can also try the steps on the knowledgebase troubleshooting guide.
http://knowledge.digi.com/articles/Knowledge_Base_Article/Digi-Connect-WiSP-WIEM-and-WIME-WIFI-TIPS-and-Troubleshooting/?q=wi-me+discovery&l=en_US&fs=Search&pn=1