Connect a Keypad 4 × 4 to the Lpc 23xx

Hi,
I want to connect a Keypad 4 × 4 to the Lpc 23xx .
I used the LCD_4bit code and after pressing the button, the character want on the LCD displayed But it doesn't Work.

Pin description for Keypad:
( Raws: P0.8 and P0.9, P0.10, P0.11 - Columns:P0.12 and P0.13, P0.14, P0.15)

This is my C Cod:

#include <LPC23xx.H>
#include "lcd.h"
#include "keypad.h"

/*******************************************************************************
* PUBLIC FUNCTION: c_read_keypad
*
* PARAMETERS:
* ~ void
*
* RETURN:
* ~ numeric value for the pressed key. Return 0xFF if no key is pressed.
*
* DESCRIPTIONS:
* Read from the keypad.
*
*******************************************************************************/
unsigned char keypad_read(void)
{
        //start the scanning process
        KP_R1 = 0;              // scan keypress on 1st row: 1, 2, 3, A
        KP_R2 = 1;
        KP_R3 = 1;
        KP_R4 = 1;
        __delay_us(30);
        if (KP_C1 == 0) return '1';             // Key '1' is pressed
        if (KP_C2 == 0) return '2';             // Key '2' is pressed
        if (KP_C3 == 0) return '3';             // Key '3' is pressed
        if (KP_C4 == 0) return 'A';             // Key 'A' is pressed, we will store as 10

        KP_R1 = 1;              // scan keypress on 2nd row: 4, 5, 6, B
        KP_R2 = 0;
        KP_R3 = 1;
        KP_R4 = 1;
        __delay_us(30);
        if (KP_C1 == 0) return '4';             // Key '4' is pressed
        if (KP_C2 == 0) return '5';             // Key '5' is pressed
        if (KP_C3 == 0) return '6';             // Key '6' is pressed
        if (KP_C4 == 0) return 'B';             // Key 'B' is pressed, we will store as 11

        KP_R1 = 1;              // scan keypress on 3rd row: 7, 8, 9, C
        KP_R2 = 1;
        KP_R3 = 0;
        KP_R4 = 1;
        __delay_us(30);
        if (KP_C1 == 0) return '7';             // Key '7' is pressed
        if (KP_C2 == 0) return '8';             // Key '8' is pressed
        if (KP_C3 == 0) return '9';             // Key '9' is pressed
        if (KP_C4 == 0) return 'C';             // Key 'C' is pressed, we will store as 12

        KP_R1 = 1;              // scan keypress on 4th row: *, 0, #, D
        KP_R2 = 1;
        KP_R3 = 1;
        KP_R4 = 0;
        __delay_us(30);
        if (KP_C1 == 0) return '*';             // Key '*' is pressed, we will store as 14
        if (KP_C2 == 0) return '0';             // Key '0' is pressed
        if (KP_C3 == 0) return '#';             // Key '#' is pressed, we will store as 15
        if (KP_C4 == 0) return 'D';             // Key 'D' is pressed, we will store as 13

        return 0xFF;                                    // if no key press, the register is 0xFF
}

/*******************************************************************************
* PUBLIC FUNCTION: c_wait_keypad
*
*
* DESCRIPTIONS:
* Wait until the key is pressed and released.
*
*******************************************************************************/
unsigned char keypad_wait(void)
{
        // The pressed key.
        unsigned char c_pressed_key = 0xFF;

        // Wait until the key is pressed.
        do {
                c_pressed_key = keypad_read();
        }
        while (c_pressed_key == 0xFF);

        // Wait until the key is released.
        while (keypad_read() != 0xFF);

        return c_pressed_key;
}