Problem in CS03

hi to all,

In CS03 t-code,

I m providing Material no., Plant, Bom Usage and Alternative Bom,

then pressing enter ,

another screen is displayed, in which all the bom component are dislayed.

Now my problem is that all this component are coming from STPO table as per my knowledge.

But for some material when i m matching o/p of cs03 against table it is not matching.

Plz help me to find out that from where this componets are coming.

Or can anyone is able to give me the tables Related to the BOM.

thanks in advance.