NAV 2016 Codeunit 5304 Outlook Sync. error

When I compile codeunit 5304 I get an error which says

could not load type below library which is of data type dotnet, the variable is XMLTextReader.

Microsoft.Dynamics.NAV.OLSync.Common.XmlTextReader.'Microsoft.Dynamics.Nav.OLSync.Common, Version=9.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

I have installed the latest version of .net on the Nav server box.

Can someone please let me know where can I find the above library.

Your help is highly appreciated.

Thanks
Regards
RJ.