2000 Volkswagen Jetta DOOR LOCKS

I HAVE A 2000 JETTA WITH A 2.0 ENGINE. THE PROBLEM IS THAT WHEN I PUT THE KEY IN THE DOOR LOCK TO UNLOCK THE DOOR AND IT UNLOCKS IT. WHEN I OPEN THE DOOR AND PRESS THE LOCK/UNLOCK BUTTON ON DRIVER AND PASSENGER DOOR, IT DOES NOT WORK. ALSO I CANNOT OPEN THE TRUNCK WITH THE BUTTON ON THE DOOR. WHEN THIS HAPPENS I JUST GIVE THE DOOR A WHACK NEXT TO THE KEY HOLE ON THE DOOR, AND IT WORKS FINE FOR WHILE AND THAN ITS STARTS TO DO IT AGAIN. COULD IT BE THE LOCK MODULE?