Condensor or Dynamic? I've been getting questions relating to this lately. Condensor mics need power to operate, supplied by phantom power down the mic cable, or by a battery inside the mic. Examples are the Shure Beta 87 (1st photo) & a Wand Type Mic used on podiums. The last two photos show an Audio Technica ATM11 that uses a single AA Battery. For phantom mics, make sure your mixer supplies it (the vast majority do now) and it is switched on. The sort of defacto standard is 48 volts, but voltages supplied can run the gamut from 9 volts on up. Only P48 mics need the full 48 volts, so if it still isn't working, read up on it's voltage needs. Dynamic mics like the legendary SM58 in the center photo don't need any power at all. Just a coil of wire surrounding a magnet. It will have a lower output than a condensor, so crank up the gain a little higher.