Hyperlink Warning Error

 I have a Hyperlink control on my Page and in the design view I get this error message where the control is, however it run and work as normal when I run the page in my local IIS.
Error Msg: Error Rendering Control - An unhandled exception has occurred Object reference not set to an instance of an object
My Hyperlink setting:
<asp:HyperLink ID="cmdActivityLog" runat="server" CssClass="buttonimage"
Height="20px" ImageUrl="~/Images/Button/BtnActivityLog.png"
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