The dimensions are 1024x256
Edit: Ok got it to work, it seems that the max width of a texture is 512 and 1024 is not supported
So I just sliced it in 2 and it worked!
I'll confirm this, some graphics cards can not deal with larger textures. 1024 would crash me every time, but 512 worked. I never made textures for other people's use so I don't know the limits of other people's graphic's cards.