Janine, its no, prob, glad to be of help though I'm not sure why you want such a large version in your sigline that will show up with every post? The version you have now is 70 X 100 pixels, 3.03kbs, so the max height you will get with that image, because, if you notice, the dimensions for sigline images is (width) 500 X (length) 100 pixels. (For example my sigline image is 495 X 39 pixels or something.) The low height but long width dimension is so that signature lines don't get too huge and 'overpower' actual posts and 'clog' threads with too much scrolling due to huge siglines which is usually frowned upon in discussion forums.
Or... what you could do, as I did for my sigline image, 'creatively crop' a long narrow section of it, again to fit the dimensions, working from the original/largest version of your drawing (make sure to save your smaller/cropped version as a diff. file so you don't lose your original though!)
The photobucket link you use for siglines here is the "URL link-Email & IM" one.