Error : "Longmode is unsupported. It is required for 64-bit guest OS support. On Intel systems, longmode requires VT-x to be enabled in the BIOS"

Hello Guys! I'm new in VMware..

I have 2 Server :

1. Server A : Support VT-X, Windows Server 2012 Datacenter Installed
2. Server B : Not Support VT-X, Windows Server 2012 Datacenter Installed

I have Installed VMware Workstation In Server A, and I also install ESXI 5.5 in my VMware.

I used freeNAS for my Storage, and the Storage come from My Laptop.

In server B I use Hyper-V, and I install Windows Server 2008 R2. And install vCenter (vSphere Single Sign On, vSphere Inventory, Client, WebClient and vCenterServer) on Windows Server 2008 R2.

Host, storage and server have been detected on my vSphere Web Client. When I install Win XP 86 bit in vCenter that was successfully, and running well.

But i got an error when I install Win 7 64 bit or Win Server 2008 64bit.

The error is

"Longmode is unsupported. It is required for 64-bit guest OS support. On Intel systems, longmode requires VT-x to be enabled in the BIOS"

I have been try to search the solution on internet.. But not work for me!

Please Help.