Entity Framework 6 / Firebird database provider compatibility issue in Visual Studio 2013 Prof

I'm using Visual Studio 2013 Professional and .Net 4.5 on Windows 7-x64. I have Firebird 2.5.4-x64 installed.

I know that others are able to use Firebird with Entity Framework 6, and I figured out several issues on my own by reading lots of blogs and stackoverflow posts. But I've tried everything I can think of and I am totally stuck. I figured before I gave up completely on using Firebird, I'd see if someone could help me figure out what I'm doing wrong.

There seems to be a lot of outdated information on how to configure firebird within visual studio, and I've tried lots of variations of them, but here is what I think was the correct process:

• I installed FirebirdSql.Data.FirebirdClient-4.6.1.0.msi.

• I verified that it updated GAC:

  The Global Assembly Cache contains the following assemblies:
  FirebirdSql.Data.FirebirdClient, Version=4.6.1.0, Culture=neutral, PublicKeyToken=3750abcc3150b00c, processorArchitecture=MSIL
  Number of items = 1
  

• I verified that it updated in machine.config files:

  <system.data>
    <DbProviderFactories>
      <add name="Microsoft SQL Server Compact Data Provider 4.0" invariant="System.Data.SqlServerCe.4.0" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91"/>
      <add name="FirebirdClient Data Provider" invariant="FirebirdSql.Data.FirebirdClient" description=".NET Framework Data Provider for Firebird" type="FirebirdSql.Data.FirebirdClient.FirebirdClientFactory, FirebirdSql.Data.FirebirdClient, Version=4.6.1.0, Culture=neutral, PublicKeyToken=3750abcc3150b00c"/>
    </DbProviderFactories>
  </system.data>
  

• I installed DDEXProvider-3.0.1.0.msi

• I verified that entries were added to the registry and that the paths were correct
• I created a new Class Library project

• I installed the following Nuget packages:

    <package id="EntityFramework" version="6.1.3" targetFramework="net45" />
    <package id="EntityFramework.Firebird" version="4.6.1.0" targetFramework="net45" />
    <package id="FirebirdSql.Data.FirebirdClient" version="4.6.1.0" targetFramework="net45" />
  

• I verified updates were made to the App.config file. (Besides trying the default App.config file below, I also tried using one like the one in this blog)

  <?xml version="1.0" encoding="utf-8"?>
    <configuration>
      <configSections>
        <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
      </configSections>
      <system.data>
      <DbProviderFactories>
        <remove invariant="FirebirdSql.Data.FirebirdClient" />
        <add name="FirebirdClient Data Provider" invariant="FirebirdSql.Data.FirebirdClient" description=".NET Framework Data Provider for Firebird" type="FirebirdSql.Data.FirebirdClient.FirebirdClientFactory, FirebirdSql.Data.FirebirdClient" />
      </DbProviderFactories>
    </system.data>
  </configuration>
  

• I successfully built the project

• I successfully added a connected to an existing Firebird db (the Firedbird data provider and data source showed up in the options)
• I tried to adde a new ADO.Net Entity Data Model, using EF Designer from database option and the data connection I had just added

• When I clicked Next I got this error:

  Your project references the latest version of Entity Framework; however,
  an Entity Framework database provider compatible with this version could
  not be found for your data connection. If you have already installed a
  compatible provider, ensure you have rebuilt your project before
  performing this action. Otherwise, exit this wizard, install a compatible
  provider, and rebuild your project before performing this action.
  

If I don't install the EntityFramework Nuget package, there is a EF 5.0 option that is enabled and I don't get this error when I use 5.0. (But I'd really like to use 6.x instead!)

Does anyone have any idea how I can get past this error? Is there something else I can look at or do to try to figure it out? Thanks for any help!