Close the current form when new form opened in MDI?

Question

private void Form1(object sender, EventArgs e)
{
if (ActiveMdiChild != null)

ActiveMdiChild.Close()

Form2 frm2 = new Form2();

frm2.MdiParent = this;
frm2.Show();

}

 

where the Teacher_Entry is a form

This code works on MS Visual Studio 2008 but not in MS Visual Studio2005 please send me the answer for this...