External Interrupts of HCS12XEP100(FREESCALE) doesn't work properly ?

hi guys,

This is my first time here in edaboard, I hope this post finds you all well ..

I have worked on HCS12XEP100 kit with a very simple project, just capturing an interrupt on port p pin 0 and toggling the state of port A. But, it never worked for me and I really don't know why !!

Need help, If you please
Thanks

CODE:
*****

#include <hidef.h> /* common defines and macros */
#include "derivative.h" /* derivative-specific definitions */


#pragma CODE_SEG __NEAR_SEG NON_BANKED

interrupt VectorNumber_Vportp void PortP_Ext_INT_ISR(void){
static unsigned char flag = 0;
PIFP_PIFP0=1; //Clear Interrupt Flag

if(flag == 0){

PORTA = 1;
flag = 1;
}
else{

PORTA = 0;
flag = 0;
}
}
#pragma CODE_SEG DEFAULT


void main(void) {
/* put your own code here */

//Ports Initialization =============
PORTA=0x00; //Initialization
DDRA=0xFF; //Output
PTP=0x00; //Initialization
DDRP=0x00; //Input (Interrupt)
//==================================

//Interrupts Initialization ========
SPI0CR1_SPE=0; // Disable SPI Channel One,
SPI1CR1_SPE=0; // Disable SPI Channel Two,
PWME=0X00; // Disable PWM Peripheral,

PERP_PERP0=0; // Pull Deivce is Deactivated.
PPSP_PPSP0=1; // Interrupt Polarity (Rising Edge).
PIEP_PIEP0=1; // Enable Interrupt
PIFP_PIFP0=1; // Clear Interrupt Flag.
//==================================

EnableInterrupts; //Global Interrupt Enable


for(; {
_FEED_COP(); /* feeds the dog */
} /* loop forever */
/* please make sure that you never leave main */
}