I have just gotten the SHOOT Intervalometer with MC-36b cord for my Nikon D3300 camera. (I have a Viltroxx for my D40 which works fine, but the cable is different).
My problem is the D3300 won't snap a picture. When I either use the manual pushbutton or the timer, the green light comes on for 1 sec, then the amber light comes on, counts the seconds for how long I have the button pushed, then goes out when I release. The manual says the green light is the focus output, and the amber light is the shutter release.
I have the camera on M manual mode, 1/100 @ F4, Shutter release mode S single frame. Kit Lens Nikkor 55-200mm zoom on M manual focus (to eliminate the problem of the camera not snapping until in focus). The Intervalometer is plugged into the M-36b socket on the side(top one with the picture that looks like a little mousepad on the cover).
Manual release: I've pushed the button for manual release, and the light blinks amber then green, counting seconds I hold it down. Camera doesn't snap a picture.
Timer: I've set up the intervalometer (5s delay, 0s long, 5s internal, N 5). Pushed timer start and it counts down, then the green light comes on for 2 seconds, the orange light flashes, the counter ticks down, repeats, when done beeps.
The camera seems to be getting a signal. When I look through the viewfinder, the Number of shots remaining in the bottom right  switches to [r09], then goes back to , then switches to [r09], etc. No pictures are ever taken. If I press the shutter release button on the camera half way down, I see the [r09], and if I press full down it always snaps a picture.
So it's not that the camera can't take the picture (due to focus or light or anything), it's just not getting the signal? Seems like the signal to focus comes in, but not the shutter release signal. (Just confirmed the focus signal - set the lens to A autofocus, Focus mode to AF-S Single-servo AF, AF-area mode Single-point AF. When I press the button the the SHOOT, the number exposures remaining goes to [r09], and the camera focuses, but doesn't ever snap a shot. If I manually press the shutter release a picture always is taken).
I've tried the same thing on Bulb mode with the intervalometer set to Long 1s, and on TIME. Not only is the lens on manual focus, I've set the Focus Mode in camera to MF also. Nothing seems to work.
Is it a bad Intervalometer? Or is there some little setting I'm missing?