The image is too large for a signature - please make it a lot smaller
And you need to use BB code to embed it, as well as the direct image URL.
The URL you tried to use was to the photobucket page, with the image within it.
With Firefox right click the image and select 'view image'.
More instructions here: http://www.7-dna.com/forums/index.php?action=vthread&forum=4&topic=262#msg2448
The final link should be like this:
(Replace the 'xx' with 'tt')