A Simple Checkbox

[krank]

I'm trying to create a checkbox that does an action when it's checked and a different action when it's unchecked. This is what I came up with but having problems:

CODE
checkbox myCheckbox "My Checkbox"            

on myCheckbox changed theState == true do
(
    if myCheckbox.state do
    (
    messagebox ("Checkbox state is on")                        
    )            
    else
    (
    messagebox ("Checkbox state is off")                        
    )
)

Thank you.

[smokin]

checkbox myCheckbox "My Checkbox"

on myCheckbox changed theState do
(
if myCheckbox == on then ( messagebox ("Checkbox state is on"))
else ( messagebox ("Checkbox state is off") )
)