problem with displaying the form into the center of the screen

I am having a MDI form and many SDI froms. I enabled a Maximize button for one SDI form.After en开发者_高级运维abling the maximize button, if I click any form, the form is not opening in the center of the screen.

It is displaying in the top left.

Is there any property do i need to set in order to bring the form into center.

The application is developed using vb.net

Thanks in advance