If it is the battery, then after some time of rest it should work, but only for a few minutes. You should be able to push buttons several times and get the battery to go low enough to cause a problem again.
When it appears not to send a signal, does the LED flash in the RF receiver? It could be picking up interference.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
