Why are my wipers always skidding?

I have gone through 4 different brands of wipers in a progressively more expensive trend over the past three months. No matter what I get, even $20 wiper blades don't work right. I use Rain-X washer fluid and it still skids across my windshield. Right now I have wipers that conform to your windshield, and they just started skidding around 5 days after I bought them. What else can I possibly do, I am tired of wasting money on this problem?