Don't worry about the asking of questions.  I once was in tech support for 3 years, so I completely understand why you are asking for clarification.  And I fully expect this to be some sort of oversight or mistake on my part.  I just cannot find it.  :(

The class used to be:

Namespace MyCompany.Providers

    Class PortalSqlDataProvider

And it is now:

Namespace MyCompany.Provider

    Class PortalSqlDataProvider

But the assembly name used to be:

MyCompany.Providers.SqlDataProvider

And now it is:

MyCompany.SqlDataProvider

In Reflector, here is how the nodes are broken down:

- MyCompany.SqlDataProvider (assembly name)
     - MyCompany.SqlDataProvider.dll (assembly)
        - References
            - DotNetNuke
            - Microsoft.ApplicationBlocks.Data
            - Microsoft.VisualBasic
            - mscorlib
            - System
            - System.Data
            - System.Data
            - System.Web
        - [blank]
            - <module>
                - derived types (none)
        - My (followed by all of the typical My stuff)
        - My.Resources
            - Resources (typical stuff)
        - MyCompany.Provider
            - PortalSqlDataProvider

If you noticed something weird above as I did, it is not a typo.  System.Data is in there twice.  However, the DNN sqldataprovider has the same thing (two different versions 1.0.5 and 2.0).  I never noticed that until now.

Just at thought  -- I pounded my head against the wall on something similar... came down to ensuing the reference are identical including case.  As an old VB programmer I was not checking case as I expected the compiler to help... but the referenced assemblies are case sensitive and being defined in strings ... no complier help to correct the case. 

Good Luck,  Paul.

Hmm, I would've assumed that my email was shown as part of my profile, but I guess not.  It's bdukes at engagesoftware dot com.