Color Sensor TCS230

Hello,
Now I am using this code http://www.elecfreaks.com/wiki/index.php?title=Color_Sensor_Module

and getting results like in the pic in this link http://www.elecfreaks.com/store/download/product/User_Guide/Color_Sensor_Module/color_sensor_module_user_guide.pdf

but sometimes I am getting some results bigger than 255...What could be the problem? Anyone can help me please?