Thank you for using Syncfusion products.
This issue will occur if the namespaces are not referred in the “Web.config” under Views folder. In Razor mode view engine, the namespace should be rendered in both “Web.config” and “Web.config” in Views folder. We suggest you to refer and use the following code snippet in your sample:
<add namespace="Syncfusion.Mvc.Shared" />
<add namespace="Syncfusion.Mvc.Tools" />
We also suggest you to refer the following documentation to
know more information on adding reference to our Syncfusion control,
Please let us know if you require any further assistance on this.