I think this is what you are running into:
http://kb.vmware.com/kb/2005793
You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier. Apple does not allow these Client OSes to be virtualized. With Mac OS X 10.7 (Lion) onwards, Apple has changed their licensing agreement in regards to virtualization. For more information on creating a Mac OS X 10.7 (Lion) virtual machine, see Installing Mac OS X 10.7 (Lion) as a virtual machine in Fusion 4 (2005334). For more information on creating a Mac OS X 10.8 (Mountain Lion) virtual machine, see Installing Mountain Lion (OS X 10.8) as a guest operating system in VMware Fusion 5 (2033778)
Try with a 10.7 and see if it works?
Regards
a