The microphone is likely an electret microphone which needs to be biased, meaning it needs a voltage across it. Your laptop does this by default, but Monotribe probably doesn't.
You could look here for example:
http://circuit-diagram.hqew.net/Battery _2671.html
That circuit is a bit overkill. you can simplify it as follows: Leave out everything except R5 and C1. Connect the other terminal of the capacitor to the output, ie the tip of the jack.
R5 should be something between 4.7k and 10k.
Vcc is the positive terminal of some battery arrangement such as 3-4 AA batteries in series, or one 9V battery. The negative battery terminal goes to ground.
C1 should be something between 1 uF and 4.7 uF. The positive side of the capacitor should be connected "up", and the negative side "down", ie to the output.
Or connect it through the mixer. That's totally cool as well.
Oh and this might be if interest as well: