How can I activate a MDI window after this one has been hidden in systemtray ?

I have tried:
Code:
ShowWindow(SW_RESTORE);
SetForegroundWindow();
is shown, but not activated. I have to click on this window in order to be activated...
also, I have tried:
Code:
ShowWindow(SW_RESTORE);
SetForegroundWindow();
BringWindowToTop();
SetFocus();
ShowWindow(SW_SHOW);
ActivateFrame(SW_SHOW);
the same result ... How can I activate this MDI window after has been shown ?