TypeLoadException in WINCE 7 with System.Xml

I went to resurrect some older code in VS2008 C#, and keep receiving this exception.
The version of the assembly System.Xml, Version=, Culture=neutral, PublicKeyToken=969DB8053D3322AC cannot be loaded by this version of the Microsoft .NET Compact Framework.

It occurs when I try to serialize an object to JSON using the newtonsoft.json.compact.dll

I feel like I’ve gotten around this before, but currently I’m drawing blanks. I reinstalled all the toradex SDKs, tried including the System.Xml directly, but to no avail.

Here’s the path the System.Xml.dll is using.
C:\Program Files (x86)\Microsoft.NET\SDK\CompactFramework\v3.5\WindowsCE\System.Xml.dll

Open to any suggestions, thanks, Matt.

It appears that the System.Xml assembly referenced in your code was built for the .NET Framework version 3.5, which is not compatible with the version of the .NET Compact Framework you are currently using. However, we are not familiar with the Newtonsoft JSON framework for .NET and there could be another reason for the issue you are observing. You may want to check if Newtonsoft provides any additional information that could help diagnose the problem.

If you have any future questions, please provide the release version of your WinCE 7 BSP, along with the version of .NET that you are using.