property not persistent

LS,

I am trying to use a property, but it keeps reverting to the orginal state. And thus keeps giving me a dialog.

I really don’t get this …

TIA !

– my script

log myUrl
property myUrl : null
if myUrl = null then
display dialog “Please enter the url supplied to you .” default answer “”
set userValue to (text returned of result)
set myUrl to userValue as text
log myUrl
end if

set executeUrl to "javaws " & myUrl
log executeUrl

it seems that had not saved the script and thus setting the property does not work.