Asset additional cost effect to the Asset Current Accumalted Depriciation

Dear,

I create a payable Invoice for Asset additional cost then I run the mass Addition create in payable then my invoice is showing in the FA mass addition screen . I select the invoice and I click on the "ADD to Asst Button" then I enter my exisiting asset number and I click on the find button then system open the add to asset screen here In this screen by default Asset type is "Capitalzied type" .

The problem is that when I add the additional charges in the exsisting asset as per the above mentioned steps then system change the current Accumalated depriciation amount why which is wrong.