using the latest version of pukka (1.6.7), when you use the script, your account isn't automatically selected. luckily, there is a keyboard shortcut to select your del.icio.us account in pukka, so you can add, in the last set of a statements, the starred line below, and everything works.

awesome script you have here!
--
tell application "System Events"
tell process "Pukka"
tell application "Pukka" to activate
** keystroke "]" using command down**
keystroke tab
keystroke tab
end tell
end tell
end tell
--