MPOS Activation get error "Device Activation Error : An error occured while communicating to server"

Hi

Try to install MPOS and activate it in computer client. When I try activate it, I get error message :

"Device Activation Error : An error occured while communicating to server"

I check using Fiddler that :

Request :

GET /RetailServer/v1/ActivateDevice HTTP/1.1

Response :

HTTP/1.1 401 Microsoft_Dynamics_Commerce_Runtime_AuthenticationFailed

I also check in RetailServer web.config that requireSSL already False

  <system.identityModel.services>
    <federationConfiguration>
      <cookieHandler path="/" requireSsl="False" persistentSessionLifetime="2:0:0" mode="Chunked" name=".ASPXAUTH" hideFromScript="true">

I using DynamicsAX 2012 R3 with Windows Server 2012 R2 Datacenter. I try install MPOS in Windows8.1 Pro

I also already follow steps in http://axbuzz.blog.com/?p=45 but when I execute command to deploy and configure Retail Server, it's failed (I get exception message below)

But I still get that error. Any hints how to solve this ?