tI've added a class to my project to create my own database provider which is
essentially identical to the SqlDatabase provider but I need to get the
connection string from a COM+ component rather than the config file.

I tried to add the database type to my config file with the enterprise
library configuration tool, but I can't select my assembly for the TypeName.
When I click Load an Assembly and select my assembly, I get the following:
There were no types found in the assembly 'moo' that implement or inherit
from the base type 'Microsoft.Practices.EnterpriseLibrary.Data.Database'.

Note that my database provider is part of the windows app that is using it
(I know it shouldn't be but for the time being, it is). If I move the class
into its own project, I can load it just fine.

I had similar problems with the RoleProvider and RuleProviders. I had a
separate project with a RoleProvider that I could configure just fine. But
when I added a RuleProvider class to the project, the configuration tool gave
a similar error when I tried to select it as the TypeName.

Just discovered that I can manually change the dataconfiguration.config to
point to the assembly I want so the problem is kind of solved. I can even
open up the app.config in the configuration tool after editing it and it
doesn't give a validation error. Would still like to know why I can't select

I think I've had a similar problem.
You mention that your classes were part of your win app. SO they were
built into a .exe.
I think you need to build them into a .dll for the ELCC to pick them up
as it starts.

So, maybe, putting them in their own Class Library project would also
work.

Cheers,
F.O.R.