Run Workstation VM In Vcenter 5

HI,

I am trying to run a VM in workstation, that is nested in VM created in Vcenter. I try to start the VM, but get the following message:

Running VMware Workstation in a virtual machine requires the outer virtual machine to be configured for running a VMware ESX guest operating system. You may not power on a virtual machine until the outer virtual machine is reconfigured.

I know you have to configure a file, but I could not see any documents on Workstation 7 configuration details.

Any help is really appreciated. (Workstation VM is linux, Vcenter vm is windows 2003)

Regards,