5
Check the following
1. Admin - > Groups, Anonymous. Is the Contact Us item allowed for Module and Block Access?
2. Admin -> Template, default. Is the Contact Us template listed or showing as a red (0). Generate it if it is zero.
Lastly if it is still not working then consider using Formulaire instead (search in modules download). I'm using it for my site and have replaced my XOOPS Contact Us form with my own Formulaire customised form.