Light sensor always getting max value
What have you selected as the analog reference? And if 'external', what is connected to the Vref pin? 

For the LDR resistances of 10K and 1K, you  Vout should be ~ 1.8v at 10K, and ~ 4.2v at 1K, and giving A/D readings of somewhere around 370 counts and 860 counts, respectively, with a 5v analog reference. 

If your analog reference selected to the 1.1v internal reference, either LDR resistance should give you the max reading, but an LDR = 20K could give just over a volt and pretty close to the reading you're getting.