I have had this happen. I bought 4 pieces of batik fabric from the same shop. I didn't have any problems with 3 of them but the 4th had skipped stitches. I changed the needle, rethreaded the machine, etc thinking that was the problem. What finally convinced me it was the fabric was when I did some test runs on that fabric using scraps. I overcame the problem by readjusting my tension. I just fiddle with it until I got it to look good. Fabric can make a difference.