I've never tried this method myself... but it seems to make sense. Maybe it will help you:
http://www.????????.com/bark.htm
Also, the happy attitude may be because you are home and your dog expects you to decide who is a threat-- this is a good thing. :) And it may also just be b/c there really is *no* threat-- again this is a good thing. :) My guess is you've never really gotten the chance to see how the reacts to a real threat (I hope)-- so I wouldn't be too worried.
as for your spelling... you're better than me... and i'm a native speaker. It always seems to work out that way. :)
-chloe