el capitan applescript messages not working

I am trying to run the following code:

The code works on Yosemite but doesn't work on El Capitan

tell application "Messages"

set c to chat 1 whose name is "chat144474270451543618"

log c

end tell

ERROR: Can't get chat whose name = "..."

Also fails: (ERROR: Can't get name of text chat id)

tell application "Messages"

set c to chat 1

set n to name of c

log n

end tell

Thanks,

A.