tmux path problem

Outside of tmux, PATH is exported and has this value:

    root@clone-messagerie[10.10.10.19] ~ # export  | grep PATH
    declare -x AWKPATH="~/SYNCHRO/lib/"
    declare -x PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/scripts/exploit--:/usr/local/scripts/exploit.tmp:/usr/local/scripts/mail:/usr/local/scripts/shorewall:/root/SYNCHRO/bin"
    root@clone-messagerie[10.10.10.19] ~ #


Now inside of tmux : 
    
    BEFORE SOURCING BASHRC_CUSTOM PATH IS /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    -bash: net.ip.private: command not found
    about to export PATH as /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    AFTER SOURCING BASHRC_CUSTOM PATH IS /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    root@clone-messagerie[10.10.10.19] ~ # echo $PATH
    /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    root@clone-messagerie[10.10.10.19] ~ #
    
    
So it all seems that tmux isn't picking $PATH.