how to tell gnome I'm using debian sid?

[明覺 <shi minjue gmail com>]

Greetings!
when i performance some
  admin on the system by click on a item in System-Administration, like network, it
pops out a window to let me choose my platform, then i choose the
debian gnu/linux, unstable/testing. why it always makes me to choose?
can i configure my platfrom somewhere so that it won't ask anymore? thanks.

-- 
My platform is debian sid AMD64 gnome.