[CentOS] Display a warning message at a certain time ?

Geoff Galitz a écrit :

> Any errors from a cron run go to your root mailbox (or whatever user's
> crontab it is, when applicable).  Check your root mailbox for an error, I'm
> assuming the PATH to zenity is not set correctly.  That is the usual culprit
> in a case like this.
> 

No mail for root.

I googled quite some more, and I still have no clue for this. Here's 
what I have so far :

# crontab -l
53 16 * * * export DISPLAY=":0.0" && /usr/bin/zenity --info --text "Test"

(yes, all on one line, the wrapping only comes from my mail client)

Still not working. Which leaves me clueless.