AutoIt searching for buttons

Hey guys i have following problem: I want to click on a button which has no ID or name just a class.

class is: "btn btn-success btn-lg btn-block Button"

My Code:

Local $oInputs = _IETagNameGetCollection($oIE, "div")
        For $oInput In $oInputs
        If $oInput.classname == "btn btn-success btn-lg  btn-block Button" Then _IEAction($oInput, "click")
        Next

What am i doing wrong? Btw: Imnew to AutoIt

Thank you