Can't open sample in VS - 'Telerik Friends'

In Win 8.1, VS 2013 update 4 with AppBuilder extension, I selected the 'Mobilewebsite Sample Telerik Friends' sample

ERROR    Cannot get sample project
The project file '(path)\Mobilewebsite-Sample-Telerik-Friends.iceproj' cannot be opened.
There is a missing project subtype.
Subtype: '{da2f9169-4696-40a5-919b-f73985228cac}' is unsupported by this installation.

Other samples seem to be ok.