won't pick up microphone sound for overdub while recording

I can record my vocals with my microphone perfectly, but when i try to overdub over my instrumental track ( that i import previously to just sing over and record ) it won’t pick up my voice or barely .
Maybe it’s some prefererences settings that i didn’t set well . I’m using Audacity 2.0.2
Thanks for your help

This set of tutorials in teh manual should help you: http://manual.audacityteam.org/o/man/tutorial_recording_multi_track_overdubs.html

Koz tested 3 real-life working solutions to develop these tutorials …

My mic still won’t pick up vocals during overdub or just a very tiny sound with hissing ! when i simply record vocals it works properly .Can someone tell me what preferences i should set up for it to work or if i’m missing something , i’m using windows 7.
Thanks for your help

Check that is not an interaction to do with Windows “communications activity”.
http://manual.audacityteam.org/o/man/faq_recording_troubleshooting.html#enhancements .

Check the drivers of your sound device are correctly matched to your motherboard:

Overdubbing is more demanding than just recording - you are playing and recording at the same time. So if it’s a USB mic or USB sound card/headset, plug it into a spare USB port, not a hub.

Match sample rates in all Audacity tracks and all devices. See here:
http://wiki.audacityteam.org/wiki/Windows_7_OS#sample_rates .

If none of the above helps (please try it first) please tell us the make and model number of the mic and exactly how it is connected to the computer. Also look in Device Toolbar and list all the devices that appear for output and input.