I am having problems transferring a variable from a form back to a module.
My module is:

Public invP, vP
Sub Mod()
..
..
UserForm6.Show
MsgBox invP & vP
..
end sub

Private Sub CommandButton1_Click()
..
invP = ListBox1.ListIndex + 1
vP = ListBox2.ListIndex + 1
..
end sub

In the routine CommandButton1 invP=1 and vP=3
when the control returns to the routine Mod they both equal zero.
Any ideas why and how to make them behave?