Dead battery - Is the alternator bad?

[3point2]

I have the positive cable connected to the batter and the negative cable disconnected. I have my meter set at 200 milliamperes and touching the red meter cable with the negative battery cable post and the black meter cable to the disconnected ground cable. And I'm getting 0 readings. I've adjusted the scale but still no readings?? What am I doing wrong?

I checked the voltage on the battery and its still reading 12.2V so the meter is working.

Thanks,
-Leo
510-710-8320