Keyless entry / electronic key

My electronic key doesn't seem to always work correctly. Sometimes the key isn't detected when I'm next to the car, so I can't open the door by pushing the door button. Sometimes when I'm in my car, it won't start and says "can't identify key" or something like that. Then after the second or third try, it seems to work again and I can start the car. I think I read something recently where a woman's kids were locked in the car! Has anyone experience electronic key issues?