Check Your config’s configuration tag! Has it any namespaces? e.g.:

<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
   <runtime>
      <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
         <dependentAssembly>
            <assemblyIdentity name="SomeAssembly" publicKeyToken="..." />
            <bindingRedirect oldVersion="1.0.0.0" newVersion="2.0.0.0" />
         </dependentAssembly>
         ...

Remove namespace!

<configuration>
...

Voilá, it starts working!

Credits to this poster.