atmega8 -Timer Problem

#define F_CPU 3686400

#include <avr/io.h>

#include <avr/interrupt.h>

ISR(TIMER0_OVF_vect)

{

  PORTB ^= (1<<PB0);   //LED inventieren

}

int main(void)

{

  TCCR0 |= (1<<CS01);   //Prescaler 8

  TIMSK |= (1<<TOIE0);  //Timer Overflow

  DDRB |= (1<<PB0);   //LED-Ausgang

  sei();

   while(1)

   {

   }

}