That won't work without some sorcery! As I understand it the problem is if you make more than the normal one partition in OS X, Bootcamp won't work to make the Windows partition. The work around I have seen is to have the one OS X partition only, then make the Bootcamp partition, then after that add the other OS X partition you want.
On a default Mac you have a hidden EFI partition, a hidden recovery partition, and the OS partition.... so three to start with. Bootcamp wants to be the fourth partition and if it can't be it won't work. If you search around you can find walkthroughs to install Bootcamp first on that fourth partition then add your extra (fifth) partition later.
All that said, why do you want a separate data partition anyway? It is normally not necessary.