VFP 6.0

I have a mainmenu form and buttons on it. Upon clicking a button, I like to close the mainmenu form and open whatever other form (more like model), and then upon close/exiting the form, I like to reappear the mainmenu form again. In the "Exit" button of the other form, I have just this "THISFORM.RELEASE" and in the mainmenu form, I have "DO FORM authform". I tried put this in the button (of the mainmenu form) and didn't work right

THISFORM.HIDE()
DO FORM authform
THISFORM.SHOW()

What do I need to do?

Chuck