Hi,
I think this is permission issue. So just follow the following instructions:
From the terminal go to that directory and to that module like cd /home/openerp/addons/modules
then run this command:
sudo chmod -R 777 *
and then restart the server and and the update module list but if you still not found your module then run this command on the directory where you module is in like if addons/your_module_name then go to the addons from the command and then run the same commad sudo chmod -R 777 *
And then restart the server and update module list this will surely solve your problem