Multisite plugin and themes

Hi , i Installed WordPressMU in order to run my sites with it , though i am using a Multisite Plugin to add sites .

The problem is : the themes i added in theme’s directory , is not listed in any blog i created with multisite plugin , even i enabled this theme .

after some playing around i figured i can edit the sites configurations from user`s page and sites which attached to my account and add the name of the themes manually .

may i know is that the default and how i can fix this?

any suggestion ?!