[WDS Driver Option] - Add driver package don't work - Reason : Driver not signed

Hello.

I have Windows Server 2012 R2 with WDS installed. I want to add 64-bit driver to my WDS
but it always finish with error and don't add driver. When I try with 32-bit driver it works, and
I have driver on my list.

But I want to work with 64-bit driver, and there is no way to sign that driver. Is there way
to disable that security option (to enable adding NOT signed drivers) ?

Thanks in advance.