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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.