form.visible

Stupid me?

I was making an webbrowser application on top of another application.
The other application: existing / microstation
My application: webbrowser
made my webapplication as a child window in Microstation.

Now added a timer control to check wether the other application is running or ended.

When added in the frmWebBrowser the timer control is also stopped when microstation is ended, so this doesn't work properly.

So I added the timer control in a second form. This works fine.
But now a I have the following problem:

I can't get the new form invisible.
The properties are default already False, but still it is visible.

Can anyone explain why / help me out.