I have the following code in my WIX project

<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://wixtoolset.org/schemas/v4/wxs"
     xmlns:netfx="http://wixtoolset.org/schemas/v4/wxs/netfx">
  <Fragment>

          <netfx:DotNetCoreSearch RuntimeType="desktop" MajorVersion="8" Platform="x64" Variable="DOTNETDESKTOPVERSION" /> 
          <PackageGroup Id="DotNetDesktopRedist">
...

In visual studio, i have installed the WixToolset.Netfx.wixext Nuget Package, and its in my WIX projects dependencies.

WHen i try and build this, im getting the following error

Error   WIX0200 The Fragment element contains an unhandled extension element 'DotNetCoreSearch'. Please ensure that the extension for elements in the 'http://wixtoolset.org/schemas/v4/wxs/netfx' namespace has been provided.

I’m really struggling, trying to work out how to use netfx:DotNetCoreSearch and get the reference working.

Any idea’s?