I am trying to use Sandcastle for generate the documentation for #xlabs project, you can see more here
https://github.com/XLabs/Xamarin-Forms-Labs/issues/393
But I am getting errors
Generating shared content files (en-US, English (United States))...
Last step completed in 00:00:00.0171
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Generating API filter for MRefBuilder...
Last step completed in 00:00:01.0557
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Generating reflection information...
[C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe]
Build started 26/10/2014 14:03:30.
Project "C:\DevApps\GitHub\Forks\XForms-Toolkit\Help\Working\GenerateRefInfo.proj" on node 1 (default targets).
PrepareForBuild:
Creating directory "obj\Debug\".
GenerateRefInfo:
MRefBuilder (v2014.5.31.0)
Copyright ¸ 2006-2014, Microsoft Corporation, All Rights Reserved.
Portions Copyright ¸ 2006-2014, Eric Woodruff, All Rights Reserved.
Loaded 36 assemblies for reflection and 21 dependency assemblies.
MRefBuilder : error : Unresolved assembly reference: System.Core (System.Core, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e) required by Mono.Android [C:\DevApps\GitHub\Forks\XForms-Toolkit\Help\Working\GenerateRefInfo.proj]
Last step completed in 00:00:05.7941
-------------------------------
SHFB: Error BE0043: Unexpected error detected in last build step. See output above for details.
at SandcastleBuilder.Utils.BuildEngine.BuildProcess.RunProcess(String fileToRun, String args)
at SandcastleBuilder.Utils.BuildEngine.BuildProcess.Build()
but I have it

Comments: ** Comment from web user: EWoodruff **
Remember that there are many different versions of the .NET Framework. Picking the assemblies from the standard .NET framework used for desktop applications won't work for portable apps, Windows Phone, Silverlight, etc.
Select the proper framework version for the SHFB project using the Framework Version project property. More likely than not, it's one of the .NET Portable versions such as .NET Portable 4.5 based on the error. Leave out the core system assemblies as references as setting the framework will do that for you.