ADB for GT-I9195

Hello,

I broke my screen and I want to use the androidscreencast in order to recover some data on my Samsung GT-I9195.
I installed ADB version 1.4.2.
When I plug my phone on my computer (win7), the phone is recognized and I can browse its content.
But the command adb devices returns nothing:
"List of devices attached:


"

Can somebody help me?

Thanks in advance.

V.