MDIChild-form doesn't call OnActivate


I have a problem with a form.
When it's a MDIChild and designed for 800 x 600 the OnActivate doesn't calls
but when a change it to fsNormal it works. The strange thing is that when
it's a MDIChild and I'm decreasing the size and move all components so that
the size is aprox.630 x 410 it works.

Thanks, Magnus.