Comments by Santossh (Top 1 by date)

Usually when a control is not placed inside any of the server control, asp.net generates the clientID same as the ID provided at design time. But if the control is placed inside a server control then, the Client ID is auto generated by asp.net. Since you might have placed the accordion panel inside a ContentPlaceholder, the client ID would have been auto - generated.

Hence, its always good to access the Client ID as mentioned above.

and also, its not a stupid question, and u r welcome for any other clarification.