On my yongnuo triggers there is also a red light that lights up on the yongnuo receiver if everything is working. If that is lighting up then it is probably a problem with the mount to your flash. Make sure you have it in the right way ! Also, I purchased two yongnuo triggers as part of a kit, one of them was DOA so it doesn't surprise me if they don't work. Yongnuo really is pretty junky stuff, but if you are on a limited budget like me it can be good enough to get you by.