What I meant was that I used the direct link to the image provided by imageshack, and then used img brackets around that. I do this to avoid the picture opening a page on imageshack when you click it. All the images are 640x426 but have varying file sizes. Out of the five images I was trying to post only one worked, and that one was around 265kb. The ones that failed were 258kb, 259kb, 280kb, and 312kb. The thing that was confusing me was the one that worked wasn't the smallest file size, so the rest can't have failed because they were too big, despite the limit size being 128kb.
I'm bad at explaining things so it's likely that I won't have made any sense whatsoever.