How do I make my custom dialog droppable in the design surface like a component?

[W@ndERR ®]

I read this in Windows Forms FAQ and made as described. But when I rebuild my project custom dialog name was changed into class name of custom dialog.
Like this:
// I have some UserControl class
[Designer(typeof(ComponentDesigner))]
class MyControl : UserControl
{
...
}

When I place it to my form I recieve some myControl1 variable but after rebuild I recieve new variable MyControl and old variable become unassigned.

P.S. Sorry for my English ;)