Hi Simone1972,
On your screen, I can see you were saving your recording to USB1; please make sure that your USB flash drive is on the list of compatible devices.
You will find it on Yamaha’s site, on the page of the PSR-SX900, under “downloads”, in the “other downloads” box.
One thing I noticed: no USB drive on this list is bigger than 32Gb; how big is yours? It may be oversized, then your keyboard can’t handle it?
One thing is difficult with my suggestion, even two: 1-the model is printed very small on it, 2- on my drives, the model code is not exactly written the same way. ( SDCZ73-032G-G46 on the list and packaging, MSIP-REM-TAD-SDCZ73 on the device... )
Regards,
Yvon