Yes. It will not work inside updatepanel. You will have to add a postback trigger inside updatepanel. specify your repeater's ID controlID. For example something like this:
<asp:updatepanel id="YourUpdatePanel" runat="server">
<triggers><asp:postbacktrigger controlid="YourRepeaterControlID" /></triggers>
<contenttemplate>
</contenttemplate>
</asp:updatepanel>