AjaxToolkit UpdatePanel

Hello, I have 2 linkbutton in the updatePanel & they are initially invisible. after click on the button outside of the updatepanel, the linkbuttons comes visible but the problem is : the linkbuttons haven't events & this error is declared : "system.webForms.PageRequestManagerParserErrorException"

If you are using javascript to alter the visibilty, try adding a script manager (if it is not added) to the page (or master page if you are using one).