RadTreeView unable to find skin 'Arrows/3DBlue'

[ashishpandey21jan]

We are using telerik old version which was using dll of rad controls.Now we are upgrading these controls to latest version of telerik and getting more code issue which was not working .

My following code is not working , So please let us know How we can fixed this issue.​

Telerik.Web.UI.RadTreeView was unable to find an embedded skin with the name '~/RadControls/TreeView/Skins/Arrows/3DBlue'. Please, make sure that the skin name is spelled correctly and that you have added a reference to the Telerik.Web.UI.Skins.dll assembly in your project. If you want to use a custom skin, set EnableEmbeddedSkins=false.

<telerik:RadTreeView ID="rtvTopLeftPatientMenu" Skin="Arrows/3DBlue" 
                            runat="server" OnNodeClick="rtvTopLeftPatientMenu_NodeClick" 
                            BeforeClientToggle = "BeforeToggleHandler" BeforeClientClick = "BeforeClientClick" >
 </telerik:RadTreeView>​​