The code is correct except that you have a typo in the control literal name:
private RadButton button = null;
protected override void CreateChildControls()
ScriptManager sm = ScriptManager.GetCurrent(Page);
if (sm == null)
//add a new script manager if one has not been registered yet.
sm = new ScriptManager();
sm.ID = "ScriptManager1";
button = new RadButton();
button.OnClientClicking = "CustomAlert";
button.ID = "RadEditor1";
Literal scriptLitral = new Literal();
For your convenience I have attached my test web part.
All the best,
the Telerik team
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