"This resource does not exist, or cannot be accessed by the current user. You are currently logged in as ..." error

[Traductanet Com]

Hello,

I'm having trouble sharing the course I created with the "Students allowed to access list". I have set the course availability to "Public - No registration" and added a series of gmail addresses in the "Students allowed to access" list, but if I try to access with one of those email addresses I get the error "This resource does not exist, or cannot be accessed by the current user. You are currently logged in as ...". I've double checked and the address is correct, what am I missing?