Problem with size of Datagridview in Sub form

Question

Hey,

I have a problem again.
I have a main form with some buttons (menu) if u click on a button the form will be included with panel1.Controls.Add(form) in my main panel, the Anchor of the main panel and the datagridview in the sub form is: top, bottom, left, right.
But if I maximize the form, the width of the datagridview in the sub form doesn't change.
Can anyone help me?

Thanks