Make sure that when you put the image link between the [img] brackets, that you are using the right link. You'll want to copy the "Image Address", not the url itself. To do so, right click on the picture and click "Copy Image address" and then paste it between the img brackets.
EDIT: Ah looks like you figured it out while I was posting, but for future reference, that's another way you can do it if it's not working correctly. c:
