[gentoo-user] TMux bindkey with "-"

Hi

here

    http://blog.hawkhost.com/2010/06/28/tmux-the-terminal-multiplexer/


I found the hint to do the following key binding:

    unbind %
    bind | split-window -h
    bind – split-window -v 


But doing so results in the following message on the console, when
starting tmux

    /home/user/.tmux.conf: 5: unknown key: –

Nonetheless tmux starts.

How can I acchieve the correct binding of the keys?

Thank you very much in advance for any help!
Have a nice weekend!
Best regards,
mcc