Unable to trap error on NAS drive mount failure

Question

Following script works fine when NAS is on network but unmounted but fails to trap error when NAS not on network (it's on a wireless connection that drops out in heavy snow).
I want to build a loop so that it tries to bring up the drive every few minutes but can't prevent the error: "Connection failed. Server may not exist or is not operational at this time....... OK"
Any ideas why?
-- Connect to Remote Backup NAS
tell application "Finder"
set disk_names to list disks
if disk_names contains "dbqwbackup" then
display dialog "Backup Drive dbqwbackup connected" buttons "Connected" default button "Connected" giving up after 4
else
display dialog "Mounting dbqwbackup" buttons "Mount Drive" default button "Mount Drive" giving up after 3
try
with timeout of 250 seconds
mount volume "afp://192.168.0.18/dbqwbackup"
end timeout
display dialog "Backup Drive dbqwbackup connected" buttons "Connected" default button "Connected" giving up after 4
on error error_message number error_number
display dialog error_message & return & error_number with icon 2 giving up after 10
return
end try
end if
end tell

Answer 1

I had the same problem. I found out that a +tell application "Finder"+ block around the +mount volume+ command make the +with timeout+ to work just fine.
Hope this helps.
try
with timeout of 250 seconds
tell application "Finder"
mount volume "afp://192.168.0.18/dbqwbackup"
end tell
end timeout
end try