Partition scheme error. Unknown special file or file system.

I install now FreeBSD by the own partition scheme. I want do few partition. Most important is /boot and /etc but after create partition table FreeBSD do not want to install system. It's back doesn't understand for me report;

error mounting partition /mnt/etc/: Mount: /mnt/etc: unknown special file or file system
What type partition must have /etc/ if s set freebsd-ufs then is inpossible to mount...
Don't put them on a separate partition. If you do the system will not be able to boot.
I am after partitioning and installation FreeBSD. I must have windows for some programs, and I want to install it at second system (or in wirtual machne). I was save 50GB as free space and windows do not want to install on GPT partition because this is a GPT partition sheme and hardware maybe mot boot from this partition... Is any way to install it on this partition?