hi all. I have ArcGIS 9.3 in my pc, but I can't use all tools of this program, same of them I can use but same of them I can't. for example spatial analyst tool, when I want to use it there cames a littel window and says "you do not have necessary license to execute this selected tools". can anyone help me what I have to do to use this tools? what I have to do to correct this problem?