I understand how to add the images using the method you described. The problem is with threads that already exist. I was using standard html in previous posts. Here is an example of the code I used.
HTML Code:
<a href="http://paulberge.smugmug.com/photos/169610971-L.jpg"><img src="http://paulberge.smugmug.com/photos/169610971-S.jpg" border="1"/></a>
Using the above code generates the following link within the post.
HTML Code:
http://paulberge.smugmug.com/p hotos/169610971-L.jpg
Notice the extra 2 spaces in /photos/.
I have been posting my photographs on the forum for a while now and this method has never given me any problems. There are around 30 threads that now have broken links to all the posted pictures.