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:
Hey I found a solution to this via mkh at
https://groups.google.com/forum/?fromgroups=#!topic/android-developers/0-RzE0v-G3k
Try this (as quoted from the above source)
When the Nexus 7 is plugged in there is a persistent notification that indicates "CONNECT AS / Media Device (MTP)". In this state adb devices will not show the Nexus. Not exactly obvious why, but I you select the second option "Camera (PTP)" the device is available for debugging. This choice is persistent, and I'm guessing that with a band new device it will connect as MTP until told otherwise