Sorry for removing your sig just as you figured out how to do it, but the height limit is 250 pixels including any text that you are using and not just for the image alone. Your text put you over 300 pixels.

If you're not sure about the sizes, show me what you want to use and I'll let you know if it fits the limits. But if you right click on an image and go to Properties you will find the height and width dimensions as well as the kb size. If your image alone is 250 pixels in height then any other text will put you over.