Hi Saurabh,
Please check allocation structure and source structure.
Also investment profile you should have AuC per source structure and source assignment Check activated.
this will create AUC as per source structure and these source structure will be mapped with concerned cost element group. for example if you have 10 source structure than system will create 10 AUC for that WBS.
than you will be able to track as per cost element group in AUC.
thanks
Sunil