Subwindow error

[Dayakar]

Hello,

I have coded the following script to the button "micron". 

on arrowKey theKey
  if theKey is "down" then popup btn micron  at 230,225 
end arrowKey

on menuPick theItem
  set the label of the btn "micron" to theItem
  set the menuMode of btn "micron" to comboBox
end menuPick

The popup menu would be displayed when down arrowKey is pressed. But, the
following error is generated when ever the down arrorKey is keyed in for
the first time after opening the main stack.

Error:
------
 Type   :  subwindow: can't find stack or button
 Object :  micron
 Line   :  popup btn micron at 230,225
 Hint   :  true

Could anyone please tell me where I am going wrong.

-- 
Thanking you,

Dayakar N