One thing to be careful about is make sure you copy the entire address of your picture to put between the "img" things. Sometimes you may think you've copied the whole thing, but you may have missed a bit.
That's what happened to me! I KNEW I was doing everything right, followed everyone's advice, but could NOT get some pictures to post. Then I discovered that when I clicked and copied the addresses, for some reason it didn't copy the very end of the address. Once I confirmed I had the whole address, the pix posted no problem!!
Good luck.
The more pix posted, the better, I say!