Timeout waited for PIC

Hey everyone, I need some help here. I've so far writen the program as below and I've managed to get the hex file. I'm trying to download the program into a PIC18F452. FYI, I'm using a 40-pin enhanced start-up kit. When I try to download the file and click "start bootloader", the message " error :timeout waited for PIC" comes out. Any idea what I'm doing wrong? I really need some help here. Is it anything to do with the settings? I've set the flow rate to "software", but still no change.

//RE2 connects to Sensor
//RD1 connects to INPUT1 DRIVING MOTOR
//RD2 connects to INPUT2 DRIVING MOTOR
//RD3 connects to INPUT1 BRAKING MOTOR
//RD4 connects to INPUT2 BRAKING MOTOR
//RC2/CCP1 connects to EN1 (RMotor)
//RC1/CCP2 connects to EN1 (FMotor)

void initialize(void);
void drivingmotor(unsigned char);
void brakingmotor(unsigned char);

unsigned int fsensor;

void main(){
initialize(); //Call initialization function
PWM_Start(); //Start PWM for CCP1
CCP2CON = 0x3C; //Start PWM for CCP2

drivingmotor(256); //Forward with full speed
while(1) // Loop forever
{
fsensor = ADC_Read(1); // Sensor input value

if (fsensor > 1.30)
{
brakingmotor(256); //Braking at 100%
}

if (fsensor < 1.30 && fsensor > 0.68)
{
brakingmotor(192); //Braking at 75%
}

if (fsensor < 0.68 && fsensor > 0.55)
{
brakingmotor(128); //Braking at 50%
}

if (fsensor < 0.55 && fsensor > 0.44)
{
brakingmotor(64); //Braking at 25%
}
}

}




void initialize() { // Initialization function
PORTE = 0; // Set PORTE to low
TRISE = 255; // Set PORTE as input
ADCON1 =0x80; // Set AN0-AN7 to analog input
PORTD = 0; // Set PORTD to low
TRISD = 0; // Set PORTD as output
fsensor = ADC_Read(1); // Capture initial Sensor value
PWM_Init(5000); // Initialize PWM module with 5k frequency
CCP2CON = 0x30;
}

void drivingmotor(unsigned char speed) //Driving motor function
{
PWM_Change_Duty(speed); // Set motor speed
PORTD.F2 = 1; // Control IN1 MD1
PORTD.F1 = 0; // Control IN2 MD1
}

void brakingmotor(unsigned char speed) //Braking motor function
{
PWM_Change_Duty(speed); // Set motor speed
PORTD.F4 = 0; // Control IN1 MD1
PORTD.F3 = 1; // Control IN2 MD1
}


I hope someone can help me in this asap, really appreciate it. Thanks.