I guess that you have uploaded the image from your computer, I would recommend you to post it up on a image upload site, where you later on could make a URL and paste it in your signature. I hope you understands what I mean. Just search on google for a "Upload Images/Pictures For Free", then it should guide you how to do things.
Not sure if you've fixed your problem, but judging from your signature not having a picture I guess not. From how I understand you need a
instead of the [SIGPIC][/SIGPIC]. First you get the picture you want, resize it as big as you want (just don't go overboard), copy the picture's URL and place it between the