Apple script error for desktop picture

[5thplayer]

i have the following code

tell application "Finder"
set desktop picture to "<bob>:<Users:administrator:Pictures>:<Earth Horizon.jpg>"
end tell

but it keeps telling me that it it "cant make **** into a file type"


can anyone tell me what im doing wrong?

i was also wondering, how can i get the script to run for more than 1 user as in i logged in as the administrator and i want it to change the desktop picture for all users.

i have tried changing the : to / but no go either, please help lol im new to applescript


im using 10.5.4 in applescript on a intel mac

thanks
5thplayer