simple script works in 10.8.5 but doesn't work in 10.10.1

[luckystone]

Hi,
I'm a newbie in Apple script. My school has script to mount a volume from share folder in Windows computer (named: servicedesk).
It worked normal in OS 10.8.5, but in OS 10.10.1 doesn't.
Can anyone help me to figure out this.
Here is script:
-----------
set loggedInUser to do shell script "whoami"
tell application "Finder"
try
mount volume "smb://servicedesk/M"
do shell script "ln -sf /Volumes/M/ ~/Desktop/M"
end try
end tell
------------------------
Out put on OS 10.8.5:
can list the M drive on /Volumes/

Out put on OS 10.10.1:
When run cmd: ls /Volumes the servicedesk appear instead M drive

Grateful for any help