Error creating control..Server tag error w/ custom control on webf

[Guest]

When I drop my custom control on my webform, I get "Error creating
control..Unknown server tag 'cc1:MyGridView'"

Here's the code, any suggestions would be appreciated. dave.

<%@ Register Assembly="CustomControls" Namespace="MyCustomControls"
TagPrefix="cc1" %>

<%@ MasterType VirtualPath="~/main.master" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1"
Runat="Server">

<cc1:MyGridView id="MyGridView1" runat="server">
</cc1:MyGridView>

</asp:Content>

 

[Guest]

fix: The ToolboxData name and class name must be the same in the class file.
They were different when I was getting this error