I have three separate websites - all fuctioning on version 4.08.02 - and all seem to be working well - except for one issue:

I recently tried to upload a new module to one of my sites using my SuperUser/Host account (Host>ModuleDefinitions>Install New Module) and discovered that the "Install New Module" button is not visible on just one of the sites - and unfortunately it is the one where i need to add the new module.   It does appear on the other two sites.

All other things being equal, could there be a permission I am missing somewhere that is causing the button to be invisible (and thereby not accessible) on one site, while it is visible on the others?  They all have the same skins, etc. 

Thanks for any feedback.

Just to save some time,  I found the problem.  It did have to do with a module container option.  Problem solved.  Thanks.

Just to add a bit to this ... all modules are installed at the host (installation) level and should be available to all portals. You don't install modules to a portal.

You can, though, install skins and containers that are specific to a portal.