in my circuit i have - 16f872

pin 1 = 0,5 to 4 v
pin 2 = 0,5 to 4 v
pin 3 = 0,5 to 4 v

pin 4 = 0,5 to 4 v
pin 5 = 0,5 to 4 v
pin 6 = 0,5 to 4 v
pin 7 = 0,5 to 4 v

then i press 1 and 4,
pin 1 = 0v
pin 4 = 0v

obs: 0,5 to 4 is variant not estable
0 v = estable


i use this circuit for read one keypad, but i can't
because 0,5 = 0 then keypress all time

can i help me?