HELP!! DJ using USB sticks but Cruzer Blade flash USB isn't recognized by turntables Pioneer CDJ-900

I’m a DJ, and I just bought 2 SanDisk Cruzer Blade 16GB flash USB sticks to use live in my DJ set, but when I got on stage to start, they didn’t work. It said they weren’t recognized or found or whatever.  Luckily I had CDs as a back-up, but if I hadn’t, it could have really hurt my career. I’m a DJ and use USB sticks to store and load my music when I play, but the SanDisk Cruzer Blade 16GB flash USB stick isn’t recognized by the turntables? Does anyone know what I can do to change that, because other cheap USB sticks work fine. I haven’t installed anything on my computer (Mac) or anything like that. Does that matter? I don’t want to throw them away.

Thank you,