I've just installed a SSD drive of 500 GB replacing the superdrive. On it I've installed Yosemite and it works fine. Further I've the original HDD with another OS X Yosemite (in the future it will be dismissed).
Now, I'd like to install Windows 7 Professional (with regular licence and DVD for installation) using Boot Camp and next, with Parallels Desktop that I've downloaded to try.
So, using Boot Camp, I did a partition of 120 GB for Windows, reducing the partition for OS X to 380 GB. At the end of installation, Windows works fine and OS X too.
But opening Utility Disk, I notice that the Windows partition is greyed and is not active and is not activable. Further, it'is renamed from "BOOTCAM" to "disk0s4". What happened?
Using Parallels for trying to use Windows on a Boot Camp partition, it's not possible to see the BOOTCAMP partition.
If you need more info, please, don't hesitate to ask to me.