It could be your photo resistor is not working or it is not making a good connection to +5V, or you have wired the analogue input down to ground not through a 10K resistor.
Remove the photo resistor and the 10K pull down and just read the pin raw. It should float and give you random readings.
The connect the photo resistor to +5V and the input, you should get a reading of 1023.
Finally connect the 10K from input to ground, then you will get a reading proportional to light.