I have a nightlights raster file of India, and i want to clip it using the block shapefile for India. There are 5500 blocks. But I can't find a unique attribute(except for serial no.) to clip the raster with, I tried doing it using ModelBuilder in ArcMap 10, but if I put the serial no. in "group by fields" there is no output(the rasters are generated but it is a blank image when i put it in arcmap). If I put some non-unique atribute, the model runs for sometime then shows error.