Invoke-Command to get Services set to Automatic on all DCs

I tried this code:

$DCs = [DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest() |
    Select-Object -ExpandProperty Sites |
        Select-Object -ExpandProperty Servers |
            Select-Object -ExpandProperty Name

    Invoke-Command -ComputerName $DCs {
        Get-Service | Select-Object -Property Name,Status,StartType | Where-Object {$_.Status -eq "Stopped" -and $_.StartType -eq "Automatic"}  |
                Export-Csv -Path C:\Temp\AllDCs_RemoteRegistry.csv -NoTypeInformation
    }

…but nothing in csv.

Alternatively, how can I get a specific Service status running on all DCs in that variable?

Probably something like:

Invoke-Command -ComputerName $DCs {
        Get-Service | Select-Object -Property Name,Status,StartType | Where-Object {$_.Name -eq "RemoteRegistry"}  |
                Export-Csv -Path C:\Temp\AllDCs_SingleService.csv -NoTypeInformation
    }

…but not until I can get the first part working.