Always store your rubbers in an airtight container - they have volatile solvents in them which can evaporate, causing the rubber to become brittle. This will create minute cracks in the edge which will leave lines.
Think about how your supplier stores them - if they are not sealed in individual plastic sleeves, they could have been on the shelf for months and deteriorated before you bought them.
I had a problem with Ettore rubbers many years ago, and I asked them at the Trade Show why I was getting streaks even with new rubbers. They were horrified - they guarantee a 'Streak Free Finish'. The gave me a box of new rubbers and told me to seal them in a plastic bag till I needed them. Never had any trouble since.