Why does my flash not work?

I just bought a flash for my Nikon and the radio flash connectors. My flash is on the stand with the umbrella, the radio connectors are on the same channel. I hit rest from my cameras tester and the flash from the umbrella works, but when I photograph the flash doesn't work! Anyone know what the problem is?

Added (1). yes I'm in Manual and the radio triggers are iTTL

Sorry i have no idea of this way.

You are using a DSLR, right?

Are you using your camera in auto exposure mode? In auto, if the flash is not needed you can't force it to fire.

Put the camera into manual exposure mode - which you are going to have to do anyway if your radio triggers are not iTTL.

Then they should fire.

If the flash fires from it's own test button, and from the trigger test button (if it has one) and from the transmitter test button, then the problem is the connection between the transmitter and the camera. They aren't talking to each other.

Make sure the transmitter is connected securely, including screwing the lock ring down. Try again. If no joy, put everything (flash, radio set, camera) in manual flash mode and try again. If that works, then your iTTL is not getting through the radio system.

If still nothing, then send the radio set back and either get a new one or get a different model.