Your images show the old cylinder sky from A4, in an awfully large scale. I would not use that sky anymore, but if you do, scale it so that it repeats 3 or 4 times. I believe the old office level contained that sky, so is was still in the A5 templates. It would make sense to convert it to a TGA for getting rid of the black seams.
I don't know if you have the latest A6 meanwhile, but if so, use a sky cube, like from the standard WAD. You don't need your above script. Assigning a sky cube texture to the sky box will suffice.
- Moved to Beginner's.