__doPostBack is not defined

Question

Im getting that error when try to call a __doPostBack on one of my pages, every page that i have in the project use __doPostBack function but in this particular page im gett

Answer 1

 this.Page.ClientScript.GetPostBackEventReference(, string.Empty); 

This trick worked for me. Still would have liked to know why it wasn't rendering...

Thank you!