So you are saying that you're using exactly the same media you were using a year ago ? Maybe you haven't stored it properly.
If you mean you're using the same make of media, bin it. Most people on here will tell you it's rubbish. Pay a little more and get some decent stuff.
Ritek may have been ok at one time, but they seem to have done away with quality control. You are now getting what you pay for. Mediocre media.