Issues With Item Category Ajax

At items page, when i choose new item and change category drop down, fields at GL Accounts will change depend on what category that i choose.
So when i choose 'components' for category, there will be 4 fields at GL Accounts and only 2 when choose 'Services'

But when i edit existing item, fields at GL Accounts will not change like before when i change category drop down.
What should i do?
Cause i didn't change or modified anything inside inventory folder.

Thx