RadDock can be pinned only if it is in DockMode='Floating". When the PinUnpin command is enabled, if you place the dock in a zone the command will not be shown: http://demos.telerik.com/aspnet-ajax/dock/examples/commands/defaultcs.aspx
The error shown usually results when the dock is initially in a zone (in the .aspx at design time) and has DockMode="Floating"
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