Maximize Problem in MDI Form.

[C# Programming]

Hi
i have a main form which set it's IsMdiContainer to True (MDI Form), and second form which set MaximizeBox,MinimizeBox to False and wrote this code to display it in MDI form :

this.frm = new Form2();
frm.MdiParent = this;
this.frm.WindowState = System.Windows.Forms.FormWindowState.Maximized;
this.frm.MaximizeBox = false;
this.frm.MinimizeBox = false;
frm.Show();

but when i run application, the MaximizeBox and MinimizeBox already exists (even when i click on MaximizeBox, it back to normal mode!) which i don't want to user interact with it. where does my problem and how to solve it ?
Thanks