factory alarm beeps but will not unlock...

when remotely unlocking my 2001 tacoma, the factory alarm is supposed to beep twice and unlock all the doors, however, sometimes it will beep twice but not unlock the doors. when this happens i hit the button again and the truck beeps once and locks the doors (as if the truck was unlocked) then i need to hit the button again and it then beeps twice and unlocks? any one knows why this happens? (my remote has two buttons but the bottom button is a panic button but i guess its broken because nothing happens if i press it, so the top button locks and unlocks)

also, why sometimes do i have to be right up to the truck for the remote to lock or unlock the truck? sometimes it will only work when i am right next to the truck and sometimes i can do it from 10 feet away...