adb cannot find my device for Android debugging. Why?

Question

1. I installed Windows USB Android SDK driver for the Android Dev Phone 1
2. I enabled all the debugging modes and stuff on the phone.
3. It even says...USB d

Answer 1

There're many reasons which can cause the problem, try:

1. Turn on "USB debugging mode" in Settings->Application->Development.
2. Reinstall device drivers.
3. Restart Window/Mac.
4. Restart device.