Could not load file or assembly 'System.Web.Mvc, Version=3.0.0.0, Elmah.MVC issue

I had this exact same issue using MVC4 with Ninject built for .Net 4.5

To fix this i had to add a binding redirect to my Web.config file: (at the end of the file, just before the </configuration> tag)

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.0.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35"/>
        <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0"/>
      </dependentAssembly>
  <dependentAssembly>
    <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31bf3856ad364e35"/>
    <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0"/>
  </dependentAssembly>
    </assemblyBinding>
  </runtime>

This forces the web server to use System.Web.Mvc 4.0.0.0 instead of an older version.