Let's verify some basics that I'm sure are correct, but best to check...
- Edit the VM hardware -> Options -> Generation Options. Verify Guest OS is "Microsoft Windows Server 2012 (64-bit)"
- Verify virtual hardware version is at least 8 or 9.
- Check assigned virtual hardware to the VM and ensure it's supported: http://partnerweb.vmware.com/comp_guide2/detail.php?deviceCategory=software&productid=19174&supRel=168,171,217,218,237,189,239,240,187&vcl=true&testConfig=16
- Are you trying to use the Paravirtual SCSI controller? If so, you need to slipstream an additional driver during install: http://partnerweb.vmware.com/GOSIG/Windows_Server_2012.html
Aside from that, what error(s) are you getting during installation/boot?