Hi Bubu,
I have followed the exact same procedure as said, in my project. But I am not able to reproduce the error.
Please take a look at the sample attached.
If the same problem occurs once again, please send your sample or modify the one i have sent. Also specify the version you have used for this.
Kindly use the seperate WebForms Forum post to post your queries on any ASP.NET products.
Thanks for your interest in Syncfusion products.
Regards,
F.Rashidha
F37735.zip