The chain bounced on the cassette (didn't engage the teeth) when the link was passing over it. Couldn't figure out why, so took to LBS. He switched the link around, saying it was on backwards. Worked fine for about 20 miles. Then it started happening again, to the point where on my ride today I switched it around again. Worked great for 15 miles, no problem, smooth as silk, and then it started again. On every pass over the cassette the link wouldn't engage. This is getting really frustrating. Any idea what could be going on here? It clearly is a function of the Connex link not engaging in the cog properly when passing over it, but why? Oh, it's a Shimano Ultegra chain and the proper link.