Sub form dominates over mainform

[lex]

I have a mainform and from the mainform
I have a timer delay to free the mainform mouse code to call a subform
This works good on previous subform

I have been trying mild methods to call the subfirm
1st turn visible true
a) BringToFront
b) BringWindowToTop
c) SetWindowPos

I replaced the Subform with a completely new Subform
(all default settings in subform)
But as soon as the subform is visible it only sits over the Mainform
No mater how many times I click on the mainform to bring to front
on the mouse down event in an object on the mainform I have BringToFront
method installed and the mainform does not come to the front.

Why