Excel documents using the Office Open XML format (xlsx) can be filled without AddIn (since ProOffice version 4.0).
In general it is recommend to install the AddIn by a software distribution.
If any Excel application is used, when <%PROOBJ%> is installing the ProNovia SAPtoExcel AddIn it may lead to an error.
The AddIn will only be installed once (or after an up-date). If the error occurred, all Excel applications must be closed and the automatic filling (or Installation) must be repeated.