Windows Server 2012 R2 Remote Desktop Services Virtual Desktop Collection Creation error

I am trying to make an RDS VDI Collection.

There are two servers:

First Computer (Windows 2012 R2 Standard)

Roles:

AD DS, AD CS, DHCP, DNS, RDS (RD Wa, RD CB)

Second Computer (Hyper-V Server 2012 R2)

Roles:

Hyper-V, RDS (RD VH)

The script what I'm trying to run:

$Domain = "bt.lan"
$HyperVOrganizationalUnit = "HV-Computers"
$DomainController = "bt-dc-01.bt.lan"
$ConnectionBroker = $DomainController
$VirtualHost = "bt-hv-01.bt.lan"
$PoolName = "DemoPool"
$VirtualDesktopTemplateName = "master-pro"

Import-Module RemoteDesktop

Grant-RDOUAccess -Domain $Domain -OU $HyperVOrganizationalUnit -ConnectionBroker $ConnectionBroker

New-RDVirtualDesktopCollection -CollectionName $PoolName `
    -PooledManaged `
    -VirtualDesktopTemplateName $VirtualDesktopTemplateName `
    -VirtualDesktopTemplateHostServer $VirtualHost `
    -VirtualDesktopAllocation @{$VirtualHost = 1} `
    -StorageType LocalStorage `
    -ConnectionBroker $ConnectionBroker `
    -VirtualDesktopNamePrefix msVDI `
    -Domain $Domain `
    -OU $HyperVOrganizationalUnit

But I'm getting back only this:

VM msVDI1: RD Connection Broker could not create the computer account object in Active Directory Domain Services (AD DS). Ensure that the RD Connection Broker computer account has permissions to create computer accounts in the organizational unit (OU), the RD Connection Broker server can contact AD DS, and a duplicate computer account object does not exist in a different OU.+ CategoryInfo          : NotSpecified: (:) [Start-RDVMRollout], RDManagementException+ FullyQualifiedErrorId : RDVirtualMachineProvisioningFailed,Microsoft.RemoteDesktopServices.Management.Cmdlets.StartRDVirtualMachineRolloutCommand+ PSComputerName        : localhost

The Certificates are set under the Deployment Settings, the AD Domain AD OU also set and the Export Location too..

And I don't know what I'm doing wrong! Anybody help me please!