I always upload pictures by either uploading them from my PC directly using this button (behold my advanced paint skills):

Or by simply copy pasting a picture I've got copied into my clipboard into the reply box. That'll trigger an automatic upload as well.
Also, when I look at the links you're trying to upload: an image in [/img] will only show if it has either .jpg, .gif or .png at the end of it's hotlink.
If you're trying to embed a picture that has already been uploaded, you can extract the correct link by right clicking the image and then copying it, as shown here:

This link adress can then be embedded by you, using
Code
[img]Link Adress[/img]
.