its usually the size of the photo that is the problem. One method is to send yourself a photo in an email, and where it says BCC choose small or medium size. When you get the email you save a copy of the photo to your album and then thats the one you use on the forum. It is very fiddly though and to post one photo can set you back 10 mins. The best outcome would be to just upload a photo as you do when you are on Facebook.