Why is spatial analyst not working?
Do the following in both ArcMap and ArcCatalog: tools > extensions > make sure spatial analyst box is checked. If the check boxes for spatial analyst are not present, then you need to do the following: Acquire the source ArcGIS software and put DVD into your computer > navigate to windows control panel > Add or Remove Programs > click the ArcGIS Desktop “Change/Remove” button > follow instructions to add spatial analyst extension > then do the following in both ArcMap and ArcCatalog: tools > extensions > make sure spatial analyst box is checked.