For Pete's Sake, don't put this whole board down for one little thing. ....perhaps the reason the blades don't work is that they were not inserted properly. I have 3 different (brands) rotary cutters...and these blades have never failed to work in any of the devices. The reason could be quite simple - and certainly not the fault of the board. Accept the help of those who are trying to help you with this problem. And don't go away mad. There is lots of good advice here - every day.
June in Cincinnati