Child Window topmost

[The_Judgement]

Hi, I'm trying to get a child window to be topmost, really is a modeless dialog box, above other normal child windows. When I create the dialog box, I call SetWindowPos:

SetWindowPos(hToolsDlg, HWND_TOPMOST, 0,0,0,0, SWP_NOSIZE | SWP_NOMOVE);

but when another child window moves or get active, it get above dialog box. I don't know why happens that.
The style of de dialog box is:

WS_SYSMENU | WS_VISIBLE | WS_CHILD | WS_EX_PALETTEWINDOW | WS_CLIPSIBLINGS

and the style of the normal child window is:

WS_CHILD | WS_VISIBLE | WS_OVERLAPPEDWINDOW

Thanks.