You've done all the code correctly! It appears that the problem might be that the site where you have the image stored does not allow hotlinking. There are many web hosts that allow people to view web pages stored there but don't allow individual images to be pulled to be displayed elsewhere, like here on the DIS.
You might check with the host you are using. Some will allow hotlinking but you have to ask them to enable it.
While you are at it, you might want to check out this link on Clipart Guidelines. When you get your linking to work, you'll need to reduce that image some before it can be used in your signature and be within the board guidelines.
This is the message I got when I tried to veiw your pictures:
A Hotlinking Error Has Occured!
We have detected a hotlinking error. Hotlinking is when you link to images or NON html files on 0catch.com from another host. Hotlinking is not allowed for our FREE Accounts. Hotlinking is allowed for our paid accounts. Your account can be upgraded in the user section when you have logged in.
That's the problem we're running into more and more. There are very few websites that allow hotlinking. I would suggest upgrading to a paid account. Another option is www.worldzone.com You have to get a premium account for $12 a year. Then you have to email them and request that hotlinking be allowed.