create dll for usercontrol

i used following one:

namespace sttTextBox
{
public partial class UserControl1 : TextBox
{
public UserControl1()
{
InitializeComponent();
this.GotFocus += new EventHandler(UserControl1_GotFocus);
this.LostFocus += new EventHandler(UserControl1_LostFocus);
}

void UserControl1_LostFocus(object sender, EventArgs e)
{
this.BackColor = Color.White;
this.ForeColor = Color.Black;
}

void UserControl1_GotFocus(object sender, EventArgs e)
{
this.BackColor = Color.Aqua;
this.ForeColor = Color.Brown;
}
}

but its not working