Oh my....
Where do I start? Well, it's a tad bit big. It's not to the power of 2 (not square), your post is a 1.2 meg bmp (needs to be TGA), don't think you have an alpha channel, etc
I can go on and on.
BUT that's not answering your question. Checking my "\gamecore\Guns\scifi\tavor\" directory, I found the 2 DDS files that are used for the scope. The sizes are (to my amazement) 1024 X 1024 and 32bit. Your image needs to be square AND the power of 2 (64 x 64, 128 x 128, 256 x 256, 512 x 512, 1024 x 1024, etc) and a DDS file saved as 32bit.
Try that first.
-This...is my boomstick!