[Closed] WPF eventhandler not working

This script works very well in Max 2019, But in older version button’s event handler doesn’t work. Any idea what is changed in 2019 which is not available in older versions?

delete objects
clearlistener()

dotNet.loadAssembly "WindowsFormsIntegration.dll"

CustAtt = attributes Tracks
(
	parameters Param_Main rollout:Rol_Main
	(
	)
	
	rollout Rol_Main "Parameters"
	(
		dotNetControl ElementHost "Integration.ElementHost" width:Rol_Main.width height:200 pos:[0,0]
		
		on Rol_Main open do
		(
			TheButton = dotnetobject "system.windows.controls.button"
			
			fn OnClick Sender Arg =
			(
				print "Clicked"
			)
			dotnet.addeventhandler TheButton "Click" OnClick
			dotNet.setLifetimeControl TheButton #dotnet
			
			ElementHost.child = TheButton
		)
	)
)

Obj = teapot isselected:true
AttMd = EmptyModifier name:"Custom"
addmodifier Obj AttMd
custAttributes.add AttMd CustAtt