PowerShell script run from c# app

Hi - I have an application written in c# that executes PowerShell scripts.
It performs well except when I try to write out database query results to an Excel worksheet. I am not sure at all what is preventing this.

                if (!fi.Exists)
                {
                    string smsg = string.Format("Script file {0} does not exist.\r\n\r\n Action can't be completed.",scriptfile);

                    MessageBox.Show(smsg, Application.ProductName);
                    return;
                }               
              
                using (new sb.Impersonator("username", "domain", "password"))
                {
                    RunspaceConfiguration config = RunspaceConfiguration.Create();

                    //create powershell runspace
                    Runspace cmdlet = RunspaceFactory.CreateRunspace(config);

                    cmdlet.ApartmentState = System.Threading.ApartmentState.STA;
                    cmdlet.ThreadOptions = PSThreadOptions.UseCurrentThread;

                    cmdlet.Open();

                    RunspaceInvoke scriptInvoker = new RunspaceInvoke(cmdlet);

                    scriptInvoker.Invoke("Set-ExecutionPolicy RemoteSigned -Scope CurrentUser");

                    // create a pipeline and load it with command object
                    pipeline = cmdlet.CreatePipeline();

                    Command cmd = new Command(scriptfile);

                    if (paramList.Length > 0)
                    {
                        foreach (object prm in paramList)
                        {
                            cmd.Parameters.Add(prm.ToString());
                        }
                    }

                    pipeline.Commands.Add(cmd);

                    pipeline.Commands.Add("Out-String");

                    // this will format the output
                    IEnumerable output = pipeline.Invoke();

                    // process each object in the output and append to stringbuilder 
                    foreach (PSObject obj in output)
                    {
                        results.AppendLine(obj.ToString());
                    }
                }

$app.Visible = $false

$wb = $app.Workbooks.Add()

$ws1 = $wb.WorkSheets.Item(1)
$ws1.Name = "File Audit"

$wb.ActiveSheet.Paste($rng, $false)