Problem: Asus Nexus 7 not recognized by adb when correctly installed and connected
Setup: Asus Nexus 7 tablet Windows 7 64 bit OS
Steps taken:
I am using Windows 8 and the only thing that worked for me was the Nexus Root Toolkit 1.6.3 where I done the Full driver configuration Guide ... but I didn't follow the instructions there I went to step 2 and only installed the Signed drivers.
http://forum.xda-developers.com/showthread.php?t=1766475