Script Task Failed

Hi,

Below is the code that checks for .txt files in specified folder.

#region Namespaces
using System;
using System.Data;
using Microsoft.SqlServer.Dts.Runtime;
using System.Windows.Forms;
using System.IO;
#endregion

namespace ST_b89e02e4ec614fe096c5ea85181cf70b
{
///


/// ScriptMain is the entry point class of the script. Do not change the name, attributes,
/// or parent of this class.
///

[Microsoft.SqlServer.Dts.Tasks.ScriptTask.SSISScriptTaskEntryPointAttribute]
public partial class ScriptMain : Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTARTScriptObjectModelBase
{

    //public object ScriptResults { get; private set; }
    public object True { get; private set; }
    public object False { get; private set; }
    #region Help:  Using Integration Services variables and parameters in a script
    /* To use a variable in this script, first ensure that the variable has been added to 
     * either the list contained in the ReadOnlyVariables property or the list contained in 
     * the ReadWriteVariables property of this script task, according to whether or not your
     * code needs to write to the variable.  To add the variable, save this script, close this instance of
     * Visual Studio, and update the ReadOnlyVariables and 
     * ReadWriteVariables properties in the Script Transformation Editor window.
     * To use a parameter in this script, follow the same steps. Parameters are always read-only.
     * 
     * Example of reading from a variable:
     *  DateTime startTime = (DateTime) Dts.Variables["System::StartTime"].Value;
     * 
     * Example of writing to a variable:
     *  Dts.Variables["User::myStringVariable"].Value = "new value";
     * 
     * Example of reading from a package parameter:
     *  int batchId = (int) Dts.Variables["$Package::batchId"].Value;
     *  
     * Example of reading from a project parameter:
     *  int batchId = (int) Dts.Variables["$Project::batchId"].Value;
     * 
     * Example of reading from a sensitive project parameter:
     *  int batchId = (int) Dts.Variables["$Project::batchId"].GetSensitiveValue();
     * */

    #endregion

    #region Help:  Firing Integration Services events from a script
    /* This script task can fire events for logging purposes.
     * 
     * Example of firing an error event:
     *  Dts.Events.FireError(18, "Process Values", "Bad value", "", 0);
     * 
     * Example of firing an information event:
     *  Dts.Events.FireInformation(3, "Process Values", "Processing has started", "", 0, ref fireAgain)
     * 
     * Example of firing a warning event:
     *  Dts.Events.FireWarning(14, "Process Values", "No values received for input", "", 0);
     * */
    #endregion

    #region Help:  Using Integration Services connection managers in a script
    /* Some types of connection managers can be used in this script task.  See the topic 
     * "Working with Connection Managers Programatically" for details.
     * 
     * Example of using an ADO.Net connection manager:
     *  object rawConnection = Dts.Connections["Sales DB"].AcquireConnection(Dts.Transaction);
     *  SqlConnection myADONETConnection = (SqlConnection)rawConnection;
     *  //Use the connection in some code here, then release the connection
     *  Dts.Connections["Sales DB"].ReleaseConnection(rawConnection);
     *
     * Example of using a File connection manager
     *  object rawConnection = Dts.Connections["Prices.zip"].AcquireConnection(Dts.Transaction);
     *  string filePath = (string)rawConnection;
     *  //Use the connection in some code here, then release the connection
     *  Dts.Connections["Prices.zip"].ReleaseConnection(rawConnection);
     * */
    #endregion


    /// <summary>
    /// This method is called when this script task executes in the control flow.
    /// Before returning from this method, set the value of Dts.TaskResult to indicate success or failure.
    /// To open Help, press F1.
    /// </summary>
    public void Main()
    {
        // TODO: Add your code here


        //Dts.TaskResult = (int)ScriptResults.Success;
        string[] files =
            System.IO.Directory.GetFiles(Dts.Variables["User::SourceFileLocation"].Value.ToString(),
            "*.txt", System.IO.SearchOption.TopDirectoryOnly);
        if (files.Length == 1)
        {
            MessageBox.Show("File exists");
            Dts.Variables["User::CheckFileExistence"].Value = True;
        }
        else
        {
            MessageBox.Show("File do not exists");
            Dts.Variables["User::CheckFileExistence"].Value = False;
        }

    }

}

}

When i run ssis package getting error as:

at System.RuntimeMethodHandle.InvokeMethod(Object target, Object arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object parameters, Object arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture)
at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object providedArgs, ParameterModifier modifiers, CultureInfo culture, String namedParams)
at Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTATaskScriptingEngine.ExecuteScript()

Here is an example I use - this requires a reference to Linq to get the files returned in sorted order:

            // Get the root and archive directories
            string rootDirectory = Dts.Variables["$Project::RootDirectory"].Value.ToString();

            // Get our file pattern search criteria
            string filePattern = Dts.Variables["$Package::FilePattern"].Value.ToString();

            // Get the files from the root directory that match our file pattern
            DirectoryInfo info = new DirectoryInfo(rootDirectory);
            FileInfo[] files = info.GetFiles(filePattern).OrderBy(p => p.LastWriteTime).ToArray();

I then loop over the list of files in the array - and process as needed.