How ****** is ******? If you use a ballpoint knit needle on woven fabric, you can get stitches that are not in a straight line as the threads deflect the needle. A sharp needle might fix this for you.
Needles are very important. Not only do you need the right needle for the job, but they need to be replaced fairly often. This may seem obvious to you. If so, forgive me. It's something I wasn't always aware of.