Try this one instead

$servers = get-content "C:\PS\list_server.txt"

$collection = $()

foreach ($server in $servers)

{

$status = @{ "ServerName" = $server; "TimeStamp" = (Get-Date -f s) }

if (Test-Connection $server -Count 1 -ea 0 -Quiet)

{

$status["Results"] = "Up"

}

else

{

$status["Results"] = "Down"

}

New-Object -TypeName PSObject -Property $status -OutVariable serverStatus

$collection += $serverStatus

}

$collection | Export-Csv -LiteralPath .\ServerStatus.csv -NoTypeInformation