Haha no problem :p
It looks like you copied and pasted the thumbnail link instead of the normal URL. If you want the normal size picture, after uploading the image you get the screen with the various codes, right at the bottom there's a code that says "Direct link to image", use that in the [ img= ] tag to post the image in full size.
If it's a really big image like yours seems to be (1218x643) it may be worthwhile resizing it so it fits the forum page to 640x480 or lower if you want it a bit smaller. Checking the "resize image" box and changing it to 640x480 (for message boards)- on the first screen of image shack where you browse for the image you want to upload - would make your
slightly edited
image look like this on the forum
[img=
http://img174.imageshack.us/img174/2269/thankyouje9nn6.jpg
]
Oh and in future if you're not sure if it will work like you said in your tester above, you can use the "preview" button before you post the message, it will show any pictures in the reply that you want to post so you can see if you've done it right ;)