$Computer = "abe.com"
$Reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $computer)

$RegKey=$Reg.OpenSubKey("SYSTEM\CurrentControlSet\services\NTDS\Parameters"
$NTDSPath = $Regkey.GetValue("DSA Database file")
$NTDSREMOTEPath =  "\$computer$NTDSPath" -replace ":","$"
$NTDSREMOTEPath = Get-item $NTDSREMOTEPath | Select-Object -ExpandProperty Length

($NTDSREMOTEPath /1GB).ToString("0.000"+" GB")

Exception calling "OpenSubKey" with "1" argument(s): "Requested registry access is not allowed."
At C:UsersDocumentsHealthCheckhardwareMonitoring.ps1:40 char:1
+ $RegKey= $Reg.OpenSubKey("SYSTEM\CurrentControlSet\services\NTDS\Parameters" ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : SecurityException

You cannot call a method on a null-valued expression.
At C:UsersDocumentsHealthCheckhardwareMonitoring.ps1:41 char:1
+ $NTDSPath = $Regkey.GetValue("DSA Database file")
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : InvokeMethodOnNull

Get-item : Cannot find path '\abc.com' because it does not exist.
At C:UsersDocumentsHealthCheckhardwareMonitoring.ps1:43 char:19
+ $NTDSREMOTEPath = Get-item $NTDSREMOTEPath | Select-Object -ExpandProperty Lengt ...
+                   ~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (\abc.com:String) [Get-Item], ItemNotFoundE
   xception
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetItemCommand