Could'nt install any other version of Wavelab since Wavelab 8

since Wavelab 8, it’s omposible to install other version of Wavelab
could somebody tell me why
i have a power book and i changed the OS from Yosemite to Sierra but it’s still the same
thanks Fabien

What is happening when you try?

telling nothing, just show the logo and crash from 8.5 version to 9.5 version