The
However it is a top-level action and it cannot be used as in your code. In fact I don't remember ever seeing it to be used in WiX based deployment definitions. Most likely what you wanted is
Step.INSTALL is a part of the Standard Actions Reference specification: https://msdn.microsoft.com/en-us/library/aa372023(v=vs.85).aspx.However it is a top-level action and it cannot be used as in your code. In fact I don't remember ever seeing it to be used in WiX based deployment definitions. Most likely what you wanted is
Step.InstallInitialize.