which esx 5.5 license allows for 16 vsmp

hi experts

I have an ESX 5.5 server, with two 8-core CPUs. I have the following license:

VMware vSphere 5 Hypervisor Licensed for 2 physical CPUs (unlimited cores per CPU). This means I would have 16 cores available to my VM

But my sole virtual machine only sees 8 CPU cores instead of the 16 that I am expecting.

EDIT:

a quick test on creating a vm shows that I can create a vm with 16 cores, but i get an error when i tried to power it on.

"Feature vsmp not licensed, requires 16 have 8".

So i guess I have a license issue. what kind of license would get me 16 vsmp?

END EDIT

Any help you can provide would be greatly appreciated.

thanks guys

davy