Trouble Powering Lapel Mic with Camera

[MalloryPosts]

I have a Canon HF G21 Video Camera (belongs to College) and a 3.5 mm lavaliere lapel microphone (belongs to me) (Sorry I can't post links). I want to use the microphone with the camera but plugging it into the mic port either makes an unholy screeching (when I plug in the adapter that has 2 little stripes) sound or is completely silent (when I put in the one with 3 stripes).

When I use the microphone on my laptop or phone, it works just fine.

Is there any thing I need to get that allows the lapel mike to work on the camera?
Do I need a power supply?

 

[gecko zzed]

If it makes an unholy screeching, that to indicates some measure of progress.

Quite possibly on the camera there is a level setting for an external mike that is set to max, and when you plug it in you get feedback via the camera's speaker.

 

[bouldersoundguy]

It would help to know the model of the mic so we could determine how it's wired.