May 15, 2020 03:44 AM|Sean Fang|LINK
I was wondering if you have completed the whole process of the installation?
It is not like installing other packages that you need to do one more step to integrate the AjaxToolKit with Visual Studio - Adding the AjaxToolKit to the ToolBox.
Could you please check if you could find "CalendarExtender" in the ToolBox as below shows?
If you could not, you might have met this common problem.
You could refer to this link to complete the installation: Add AJAX Control Toolkit In Visual Studio
Moreover, you might need to register the AjaxToolKit assembly in the .aspx Page.
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>
However, if you find that the above steps have been performed correctly and the problem still occurs, could you please provide me with more information for reproducing your problem?
That way, I would be able to target the problem and find a way to help you solve it.
Hope this can help you.