Powershell PS-Remoting SQL

function SQL($query,$Targetserver,$Targetdatabase,$username,$password){
    $conn = new-object System.Data.SqlClient.SqlConnection
    $conn.ConnectionString = "Server=$Targetserver;Database=$Targetdatabase;Integrated Security=false; UID=$username;Password=$password"  
...}
Invoke-Command -ComputerName "$TargetServer" -scriptblock ${function:SQL} -Credential $cred -ArgumentList $Query, $TargetServer, $TargetDatabase, $username, $password   

Fehler: Exception calling "Open" with "0" argument(s): "Fehler bei der Anmeldung für den Benutzer 'domain\testuser'."  

function SQL($query,$Targetserver,$Targetdatabase,$username,$password){
    $conn = new-object System.Data.SqlClient.SqlConnection
    $conn.ConnectionString = "Server=$Targetserver;Database=$Targetdatabase;Integrated Security=false; UID=$username;Password=$password"  
    Write-Host "server: $targetserver"  
    Write-host "database: $Targetdatabase"  
    Write-Host "username: $username"  
    Write-Host "pw:$password"  
    Write-Host "query: $query"  
        try{
            $conn.Open()
            $cmd = $conn.CreateCommand()
            $cmd.CommandText = $query
            $cmd.Connection = $conn

            $SqlAdapter = New-Object System.Data.SqlClient.SqlDataAdapter
            $SqlAdapter.SelectCommand = $cmd
            $dt = New-Object System.Data.DataTable
            $SqlAdapter.Fill($dt) | out-null
            $conn.close()
            return $dt
        }
        catch{
            echo "Fehler: $($_.Exception.Message)"  
            $conn.close()
            return $false
        }
}