title: Building VS2013 F# project on Heroku fails with "The required attribute "Project" In Import is empty"
body: <p>I've created an F# project using one of the Nancy templates in VS2013.
  The code is basically just what the template created.</p>
  
  <p>I can import the created .sln file into Xamarin studio and it all builds and runs without any errors or problems.</p>
  
  <p>When I try to push the project up to Heroku though I get the error:</p>
  
  <pre><code>/tmp/build_b3e2706f-20c8-421e-a1ce-781831880466/NancyFirstProject/NancyFirstProject.fsproj: error : /tmp/build_b3e2706f-20c8-421e-a1ce-781831880466/NancyFirstProject/NancyFirstProject.fsproj: The required attribute "Project" in Import is empty
  </code></pre>
  
  <p>I've set the buildpack on Heroku as follows:</p>
  
  <pre><code>heroku config:set BUILDPACK_URL=https://github.com/aktowns/mono3-buildpack.git
  </code></pre>
  
  <p>I've read that a similar error can occur if you are upgrading a project via VS2013.</p>
  
  <p>Is this the same error as I'm getting?
  Is there another buildpack I can use that resolves this issue?</p>
  
  <p>I guess I can create the solution in Xamarin but I'd like to stick to vs2013 if possible.</p>
  
  <p><em><strong></em> EDIT: **</strong></p>
  
  <p>Just noticed this in the .fsproj file:</p>
  
  <pre><code>  &lt;Choose&gt;
      &lt;When Condition="'$(VisualStudioVersion)' == '11.0'"&gt;
        &lt;PropertyGroup&gt;
          &lt;FSharpTargetsPath&gt;$(MSBuildExtensionsPath32)\..\Microsoft SDKs\F#\3.0\Framework\v4.0\Microsoft.FSharp.Targets&lt;/FSharpTargetsPath&gt;
        &lt;/PropertyGroup&gt;
      &lt;/When&gt;
      &lt;Otherwise&gt;
        &lt;PropertyGroup&gt;
          &lt;FSharpTargetsPath&gt;$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\FSharp\Microsoft.FSharp.Targets&lt;/FSharpTargetsPath&gt;
        &lt;/PropertyGroup&gt;
      &lt;/Otherwise&gt;
    &lt;/Choose&gt;
    &lt;Import Project="$(FSharpTargetsPath)" Condition="Exists('$(FSharpTargetsPath)')" /&gt;
  </code></pre>