have you entered the IMG tag in the correct place?
I found that the smaller siggys are usually entered into the "signature Picture" box...
do not upload from your computer or place the URL in this area....
upload the Disney siggy to photbucket and then use the
Edit signature area...
http://i755.photobucket.com/albums/x...6/2918671b.jpg
use the "
Edit Signature" area.... and use the IMG tags to place your siggy in your signature....
let me know if this helps!