It's because there's no shading on the texture, meaning there's little to no realistic value whatsoever. It almost looks as if you've made a box with a radial gradient of red and black with Photoshop or Fireworks or something, and just slapped them on top of a UV map you spent a really small amount of time thinking about.
I suggest you have a look at someone like millenia's work (He's made more than enough tutorials on how to texture) and make sure you've spent enough time in your 3D suite to know which pixels of each texture sheet are assigned to which parts of the different model parts (this is more than likely going to require you to make your own UV map).
That way, you can work out where to draw certain details like Shadows and highlights, as well as more creative things like scratches and damage.
