According to @greatman the vault economy API does not support "world groups" aka universes.

"""
If you are hooking to Craftconomy through Vault, it is impossible to know the world the transaction is being made so all transactions will be made through the default world (The main world of your server)
"""
http://wiki.greatmancode.com/display/CRAFTCONO/Multiworld

I believe adding API support for this could be a good idea.

Added.

Thanks man, you are the best!