Hi Mohan,
Thank you for using Syncfusion prodcuts.
The version 7.1 is almost 3 years old and we have issued about 12 major releases from that time. We have included several features and improvements for every service pack release with Essential XlsIO.
We would therefore urge you to upgrade to our latest version to avoid the above reported compatability issues. We will also help you with migration issues if any.
Please go through the following latest version link to upgrade.
http://www.syncfusion.com/downloads/latest-version
Please go through the following online XlsIO samples for your reference.
http://asp.syncfusion.com/demos/reporting/xlsio/default.aspx
Please let me know if you require any further clarifications.
Thanks,
Sridhar.S