create Windows 7 vm from scvmm r2

guys,

I have a windows 7 enterprise 64 bit, I'm trying to create a vm from scvmm 2012 R2. when I try to boot from the iso I got an error message. If I change from Genaration2 to Generation 1, it will boot and allow me to install.

what's the issue here?

Thanks.

FD