applescript property of called script not changing after loading and running

I have two scripts, callingScript and CALLEDscript. I want callingScript to be able to get any updated values of CALLEDscript properties but cannot get this to work.

My current test versions of the two scripts are:

CallingScript.scpt

display dialog "this is the start"

set theOtherScript to load script alias ((path to desktop as text) & "CALLEDscript.scpt")

run script theOtherScript

display dialog "this is nearly the end"

set receivedMessage to (theMessage of theOtherScript)

-->"blank to start with"

CALLEDscript.scpt

property theMessage : "blank to start with"

display dialog "Hello"

set theMessage to "no longer blank now"

log theMessage

Can someone please explain what I am doing wrong?