From the pictures it looks to be right in the centre of each wiper, is that right? If so, I suspect the wiper isn't applying equal pressure along either of the blades. If none of the above works, and easy way to eliminate this would be to remove the blade form the arm, manually drag it across the windscreen when it's wet (use it as a squeegee as such - be careful not to scratch the glass though) - also if you do it in a different direction to the usual wiper motion, and you still get smears in the same places then it's definitely the windscreen. If, however, you're left with a clear windscreen then it's got to be the arms.