If you have installed the drivers correctly and still no-go then try one of these three things to get the USB drivers to recognize a phone.
1: With phone plugged into computer, as fast as possible turn USB debugging off then back on.
2: With phone off, plugged into computer, turn phone on.
3: With computer off, phone on and plugged in, turn computer on.
This works on all custom ROMs.
Sent from my LG-VM670 using Android Central Forums