Error importing a file from a PX

I followed the code example from the 9.3.2 SDK Development Guide - Using Agile APIs for impoting a file into Agile and receive the error below in the Validate XML file. Can someone tell me how to code it correctly to avoid this error?

"The supplied data appears to be in the Office 2007+ XML. You are calling the part of POI that deals with OLE2 Office Documents. You need to call a different part of POI to process this data (eg XSSF instead of HSSF)"