Hi,
Thank you for the details.
I could see that the file has been created using Excel 95 which Essential XlsIO does not support. You can get the details of supported formats from our documentation linked below:
http://help.syncfusion.com/ug_72/xlsio/IntroducingEssentialXlsIO.htmlPlease go through it and let me know if you have any questions.
Regards,
Geetha