Ya i have one function which dynamically creates form design. So when i use opacity nd maximize in load event it first executes that function nd then meximizes somethime it didnt maximize..
I mean its working like 50 50.
Here's another thought a dialog form without a control box and no text has no title bar. enable autosize, autosizemode growandshrink, windowstate maximized, and size equal to the MDIParent.size, and the form will show maximized inside the parent, with no title bar, and will autosize with the parent. Since you want to create it dynamically, designing it in the VS designer then copying the code from the designer file, should give you everything you need.
I am beginning to suspect that the issue is the MDI taskbar that shows up when you maximize a child form. I have attached a simple project for you to play with.