My Custom Control and DataGrid Designer error

[Gabriel]

I'm developing a custom webcontrol. In it I override its Render
method. I've developed a class designer for it too. My control works
fine in the VS.NET webform designer but I'm getting a problem when I
want to use my control inside a template column in, for example, a
DataGrid control. The DataGrid designer shows the following message:

"There was an error rendering the control. Check to make sure all
properties are valid"

If a disable my class designer the error occurs too.
I've seem that most of built-in webcontrols in the .net framework
override the AddAttributesToRender method instead of the Render
method.

Any help is appreciated. Thanks in advance.

Gabriel