OK, the error message indicates you are not allowed to access the resource.
You didn't mention it so I bet you didn't use session, did you?
In the platform settings, what are th files and directory settings (777....)?
Note that this only will be available for NEW directoris, not existing one.
If you are on a test platform, then try to assign 777 to the course directory and sub-directories (the command under Linux is, if your course name is MyCourse:
Go to courses directory, then type chmod 777 -R MyCourse
Press return key.
Note this gives ALL rights to everybody.
From here you ensure that at least the user has access to the resource, this may ndicates whether it's a config or right issue.
THIS IS FOR TEST PURPOSE ONLY, don't do it on a production platform