Declare global variable in Application level

Hi,
I need to declare a global variable in Application level not Module level.
I have declare a variable in Module1 and then Module2 with same name then complile it and get success. That means there has two variable with same name in different Module. I think this was not a proper global variable declaration by which I can allow to declare only one variable in all Module, Class every where. I have used code as below -

Option Explicit
Public MyID As Integer

Thanks,
Suman