If you are going to create a complex sequence of macros, it is a good idea to declare your variables using a Dim statement in each subroutine. This prevents any confusion over whether a variable is local to a subroutine or a global one (variables declared outside of subroutines are global). For example:
Sub MyTest
Dim x, y
x = 24
x = "Hello"
y = 12
x = x & " " & y
End Sub