Hardware "The game cannot be started. The data is corrupted." Infinity Firmware Builder

[PannenkoekenNL]

I am following this guide: http://hackinformer.com/PlayStationGuide/PSP/tutorials/how_to_install_661_infinity.html but I keep getting "The game cannot be started. The data is corrupted." when I try to run 6.61 Infinity Firmware Builder. How can I solve this? I have already tried to download the files again and put it on my PSP Go.

Edit: Solved, you need to have the PSP running CFW already