Program started from cron cannot open display:?

[John Ericson <john@john.pp.se>]

I'm trying to launch a local Gnome program on my local X from crontab but in my
mail report from the cron it says:

Gtk-WARNING **: cannot open display:

And the program won't come up. My display is :0 and yes, X is running.

Can anyone give me a hint here? 

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