Square wave frequency meter /Interrupt not occur

#define _XTAL_FREQ 16000000

#define RS RC0
#define EN RC1
#define D4 RC2
#define D5 RC3
#define D6 RC4
#define D7 RC5

#include <xc.h>
#include "lcd.h"

//BEGIN CONFIG
#pragma config FOSC  = HS
#pragma config WDTE  = OFF
#pragma config PWRTE = ON       // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)...