Photo resistors reversing values on Arduino

Hello I am using 6 photo resistors/LDR's with an Arduino Mega 2560, the LDR is connected to +5V then the other leg of the LDR goes to the control cable in the Arduino (A0-A5) then finally a 10K resistor to the Arduino's ground. The aim is to make a laser harp, with the photo resistors producing a high resistance when light is upon them and low when the beam has been broken (or the opposite way around), however I have an intermittent problem were random LDR's invert the value making the LDR's perform in the opposite manner whilst the other's function as intended. Has anyone experienced this before or have suggestions?

The code on the arduino is:

int sensVar;

void setup () {

Serial.begin(9600);
}

void loop () {
for(int x=0; x
sensVar=analogRead (x);
Serial.write(x);

Serial.write(sensVar);

}

}

This is fed into a max patch