Hi,
Got the the same issue. I've enabled the Workflow for the Documents Module, I've set which users have the right to add/edit/delete documents and which users are allowed to publish/approve documents.
I can add documents to the repository, the trick to get passed the Access denied error was to check the Save files in the database checkbox in the basic settings page of the Documents module.
The problem now is that when I try to send a request for approval I get a weird error and I don't know why. The Workflow module works for ExtendedHTML module so I figure it must be something with the Documents module.
I'm using Rainbow 1.5, just installed it.
Anyone any suggestion?