I have added AjaxControlToolkit for .NET 4 into my web form project through Nuget. But I cannot add the controls into my Toolbox in Visual Studio. The steps of adding the controls I used are exactly same with the answer of this post, but after I selected the .dll file and click "Open", this error keep coming up:
There are no components in 'My Project Location\packages\AjaxControlToolkit.7.0725\lib\40\AjaxControlToolkit.dll' that can be placed on the toolbox.
My project is using .NET 4 also, I have checked it. I have done some research but there is no solution for this problem online! I also tried to add the toolkit from the zip file downloaded from the official website, same error! I don't know whether it is a Visual Studio problem. Please help me! This troublesome mystery has puzzled me for many days...
Thanks in advance!