If the Excel file source code is in the html format, the POI is not able to read that file. While if it is in the default binary format it does.
If its in HTML then use an HTML parser. My tape player doesn't play CDs if I stick them in the cassette deck so i stick them in the CD player part.
Actually I didnt want to parse the source through a parser. My primary objective was to convert the existing Excel file to an Excel file which will have source as binary.