Hi Ron,
Thank you for your interest in Syncfusion products.
I was not able to reproduce the issue. I have created a sample using your code snippets and it is working fine for me. You can check it in the following link:
http://websamples.syncfusion.com/samples/XlsIO.Web/6.3.1.8/I50411/main.htmCould you please try running the sample from the above link? If you still face issue, please send us your file so that it would help us to find the cause of the problem.
Please let me know if you have any concerns.
Regards,
Geetha