1. What brand of blade are you using?
2. Where did you buy the blades?
3. Were they in individual packaging or as multiples in a package?
4. How are they stored?
In over 30 years of teaching, I have found that all 4 of these questions' answers have relevance to the issue.
I ALWAYS buy Olfa blades, never at joann's/walmart/etc., and I keep them stored in the original packaging where they are not exposed to contact with other tools or dampness. It is my intuition that you have gotten a bad batch of blades.
I look forward to your responses.
Jan in VA