Not making any assumptions, You have to have Windows installed in the VM before you can install Office. If you have installed Windows, then I would think that the issue is that the OS or Win Installer is corrupt. You could try to repair the OS using setup options by opening the VM and then launching the Windows installer from the ISO file that you used to install Windows.
Thanks for the post. Yep, I have Windows installed and I also tried your recommendation. Still no luck. I'm not sure what it could be. The same CD worked perfectly on my iMac, but that is running bootcamp and partitioned Windows.