Can you give some more insight in the actual problem?
Is this Ebom setup with regular BVR (Bom View Revision) or 4GD?
Are you using the Teamcenter RAC - Structure Manager, MPP, ... application?
Did you used the old Classic/modular Variants or the new Product Configurator to setup the variability?
Is it working in the Rich Client but not upon exporting this to Excel?
Some screenshots can also help