dynamic onclientclick() attribute & User control

 Hi,
i have a user control using some modal popups which are based on a hidden button within the same user control.
i want to add attributes like  OnClientClick="usercontrol_hiddenbutton.click()" for the submit button on the parent form of the user control.
I tried to set the attribute in the page_load() of user control using something like this :
       Button cc = (Button)upPopup.Parent.Parent.FindControl(TriggerButton);
        cc.Attributes.Add("OnClientClick", this.waitbtn.ClientID + ".Click();");
although in the html it is added but somehow this is not working.  I want to fire the clientside click event of usercontrols button from the main page which contains the user control.
Any Ideas ?
Plz help !!
 
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