mdi parent and child

Question

i have 3 forms.

 

form1 is main form i.e parent form and ismdicontainer propery set to true in form1.

//here is form 1 button click for form 2 open
private void button1_Click(object sender, EventArgs e)
{
Form2 f2 = new Form2();
f2.ShowDialog();
}

now i want to form 2 button click then form2 close and form3 open a child in to form1 parent.

trying below code

// form2 button click for form3 open and form 2 close
private void button1_Click(object sender, EventArgs e)
{
//hide form2
this.Hide();
//open form 3
Form3 f3 = new Form3();
f3.MdiParent = Form1.ActiveForm;
f3.Show();
//close form2
this.Close();
}

form 2 closed but form3 not open as a child form3 to parent form1.

 

please share correct code.its helpful for me.iam new in this.just iam learning and try to make small application.

sorry for my bad launguage.