Arduino Due Strange AnalogRead Values

here is the code for to test:

double e;

void setup() {

Serial.begin(9600);
analogReadResolution(12);

}

void loop() {
// read the value from the sensor:
e=analogRead(A0);
delay(1000);

Serial.println(e);

}

i dont know why the values are so low.. monday i will try it with another arduino due..