UBB.threads PHP Forum Software Community Forums Resources and Customizing How Do I? Viewing attachment w/in a post

You need to increase the attachment size to enable it to be visible as an image.

CP > Display Options > General > Primary (tab) > Topic Display Options > Max Size for inline uploaded images

I have mine set to 524288 so any image attachment up to 500k will display inline as an image and anything over that will display as an attachment.