reporting

Hi Gurus

      I am having report on inventory ageing pleasse let me know if any one had worked on inventory ageing i am having report that is i am having requirement like this i am having three buckets like agein2g for 1year nd bucket is ageing between 1-3 years and 3rd bucket is more than three years can anyone help me how to write logic in bex reporting so that it could be helpful me a lot

Thanks