JS 4.4 Swap 2d - 3d problem

[TubaKumbara]

Hello.

Im trying to swap 2d - 3d

ArcGIS API for JavaScript Sandbox 

But i'm getting an error message on this line

appconfig.activeView.viewpoint.clone();

Error message is : "Unable to get property "clone" of undefined or null reference.

My code same as your sample code

Thanks inadvance

[ThomasSolow]

Your sample seems to work fine for me (checked with chrome and firefox).