How to add some amount to existing asset in asset module directly?

Dear Experts,

I have one requirement, add some amount to existing asset in asset module. I have created new mass addition in prepare mass addition window and enter Transaction date, Date in place, cost and Units. After save the data , added to existing asset. Then make new as Post. After that I run the Post Mass addition Program , But the cost was not added to existing asset. No lines are showing In Mass addition posting report. why it's happen?  Am I missing any data to enter? Is there any Standard API for Mass addition? Please guide me.

Thanks,

Aswini.