Arduino-4X4 matrix keypad with I/O shift register - arduino

Question

I need help. I have done some research and my little understanding of keypad scanning is that the ShiftIn value of Input Column should return zero (0) when a keypad button is pressed. Mine is only returning 255 (or 11111111) in BIN. All I need is to track the zero value when a key is pressed and then scan the keys matrix to display the pressed key. I will appreciate any help. I have added my code and schematic.
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const int kbdRows = 4;
const int kbdCols = 4;
int LatchIn = 2; //165 pin1
int ClockPin = 3; // 595 pin11 & 165 pin2
int DataIn = 4; //165 pin9
int LatchOut = 5; // 595 pin12
int DataOut = 6; //595 pin14
int led = 7;
int PinState = 0;
char keys[kbdRows][kbdCols] = {
{ '1','2','3','4' },
{ '5','6','7','8' },
{ '9','0','A','B' },
{ 'C','D','E','F' }
};
byte KeyIsDown() {
int row;
int col;
int rowBits;
int colBits;
rowBits = 0X10;
for (row = 0; row < kbdRows; row++) {
digitalWrite(ClockPin, LOW);
digitalWrite(LatchOut, LOW);
shiftOut(DataOut, ClockPin, LSBFIRST, rowBits);
digitalWrite(LatchOut, HIGH);
delay(5);
digitalWrite(ClockPin, HIGH);
digitalWrite(LatchIn, LOW);
delay(5);
digitalWrite(LatchIn, HIGH);
colBits = shiftIn(DataIn, ClockPin, LSBFIRST);
for (col = 0; col < kbdCols; col++) {
if (colBits==0) {
// not sure what condition to put here
byte keypressed = keys[kbdRows][kbdCols]; here
// I know this is the right stuff to return here
}
return colBits;
colBits = colBits >> 1;
}
rowBits = rowBits << 1;
}
}
void setup() {
pinMode(ClockPin, OUTPUT);
pinMode(DataOut, OUTPUT);
pinMode(DataIn, INPUT_PULLUP);
pinMode(LatchOut, OUTPUT);
pinMode(LatchIn, OUTPUT);
digitalWrite(LatchOut, HIGH);
digitalWrite(LatchIn, HIGH);
Serial.begin(9600);
digitalWrite(led, HIGH);
}
void loop() {
byte retColBit = KeyIsDown();
Serial.print("ColBit: ");
Serial.println(retColBit,BIN);
delay(500);
PinState = digitalRead(DataOut);
Serial.print("DataOut: ");
Serial.println(PinState,BIN);
delay(500);
}