ADC ATMEGA16 microcontroller

Hy.
I use for the first time ADC of ATMEGA16 16PU 1010K microcontroller.
I dont understand why the least four signifiant leds doesn't turn on.
Always the most four signifiant leds are on.


void ADC_Setup()
{
   ADMUX = (1<<REFS0);
   ADCSRA = (1<<ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
}
unsigned int ADC_Read_Channel(unsigned int ch)
{
   ch &= 0b00000111;
   ADMUX = (ADMUX & 0xE0) | ch;
   ADCSRA |= (1<<ADSC);
   while(ADCSRA & (1<<ADSC));
   {

   }
   return (ADCL);
}
int main()
{
   unsigned int rezultat;
   DDRA = 0;
   DDRB = 0xFF;
   ADC_Setup();
   while(1)
   {
      rezultat = ADC_Read_Channel(0);
      if(rezultat < 70)
      PORTB = 0xF0;
      else
      PORTB = 0x0F;
   }
}