execute powershell in c# (error) [closed]

I am trying to execute a PowerShell script in C#, but I get a ParameterBindingException and I am pretty much stack.

private string path = @"d:\\foo.ps1";

private string RunScript(string scriptText)
{
    Runspace runspace = RunspaceFactory.CreateRunspace();

    runspace.Open();

    Pipeline pipeline = runspace.CreatePipeline();
    pipeline.Commands.AddScript(scriptText);

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

    Collection<PSObject> results = pipeline.Invoke();

    runspace.Close();

    StringBuilder stringBuilder = new StringBuilder();
    foreach (PSObject obj in results)
    {
        stringBuilder.AppendLine(obj.ToString());
    }

    return stringBuilder.ToString();
}

private string LoadScript(string filename)
{
    try
    {
        using (StreamReader sr = new StreamReader(filename))
        {
            StringBuilder fileContents = new StringBuilder();

            string curLine;

            while ((curLine = sr.ReadLine()) != null)
            {
                fileContents.Append(curLine + "\n");
            }

            return fileContents.ToString();
        }
    }
    catch (Exception e)
    {
        string errorText = "The file could not be read:";
        errorText += e.Message + "\n";
        return errorText;
    }
}

private void button1_Click(object sender, EventArgs e)
{
    RunScript(LoadScript(path)); 
}
}