Problem with internal reference on breadboard

Hi! I got my atmega328 on a breadboard using Arduino - Home and it works just fine with a NRF24 on the breadboard powered by 2xAA. But when I try to use the analogReference(INTERNAL) that doesn't work, the ADC uses 3V (2xAA) instead of 1,1V.
I'm using a voltage divider to get 1,1V and I have measured it with a multimeter so thats not the problem. 1,1V returns 342 (1023/3) instead om 1023.
My setup() looks like this (+ stuff to get the NRF24 working). I'm not switching reference at any time.

void setup()
{
    analogReference(INTERNAL);
}

Thanks!

Could you power it with 5V ?
And make a small test sketch to set the analogReference and read an analog input and display it on the Serial monitor. Upload that sketch, so we can check it.
If your hardware is okay, I'm 100% sure it will work after that.

Did you connect anything to Vref ? (100nF or nothing is okay).
Did you power the AVcc ?
Is the analog mux used for anything else ?

Erdin:
Could you power it with 5V ?
And make a small test sketch to set the analogReference and read an analog input and display it on the Serial monitor. Upload that sketch, so we can check it.
If your hardware is okay, I'm 100% sure it will work after that.

Did you connect anything to Vref ? (100nF or nothing is okay).
Did you power the AVcc ?
Is the analog mux used for anything else ?

The AREF was connected to the battery as in the guide i linked. I though it was only used when you called analogreference(EXTERNAL). When I disconnected it I got 1023. Thank you very much!

I called it accidently Vref, but it is Aref.
And it should be left open. The tutorial is wrong.

With an external reference, it can be used to apply a reference voltage to it. For example with a high accurate voltage reference for a measuring device (the Arduino as voltmeter). But in most cases the internal or default reference is used.