Onclick function is not called after __doPostBack!!!

On client click the validateDialogValues function will be called and if everything is ok the following line is executed __doPostBack('ctl00_ContentPlaceHolder1_Button1', ''), after that the OnClick function should be called btnContinue_OnClick in cs file but for some reason this function is never called.
 
My Button:
asp:Button Go to the complete details ...