Help me setting MIDI buttons

[psicho]

Hi, I've got a problem when using my behringer BCR-2000 with Live 4.

When I set up a button on the BCR to work with a mute it works if I must take OFF the mute but when I press it again it doesn't work anymore!

I can't figure out what to do to set the same button to switch ON/OFF with the mute!!