The problem is not with booting into the installer. That works just fine but when I try to use disk utilities to format my ssd it is not recognised.
As I stated before, the problem is not with the usb stick or the installer. The installer boots just fine so the usb stick has to be ok. The problem that I have is with the ssd which is not recognised during the installation process. The ssd that I want to use to install Sierra contains a working El Capitan installation, so there can't be a problem either or else I'm sure it would not boot.