为什么此MessageBox没有出现？

Question

I Have Code for EventHandler like this below.

void ConnectionManager_Error(object sender, EventArgs<string> e)
{
    BeginInvoke((MethodInvoker)delegate()
    {
         State = ConnectState.NotFound;
         MessageBox.Show(e.Value);
    });
}

My Problem:

MessageBox never appears even when the device is not connected to the computer.

I think that comes MessageBox supposed that show error messages. Can someone show me what is wrong?

Note:

I have this code that I thought would trigger ConnectionManager Error EventHandler.

private void LogError(string error)
{
    if (Error != null)
        Error(this, new EventArgs<string>(error));
}

I also have this code that gives an error message containing the string to LogError method.

int lasterror = Marshal.GetLastWin32Error();
    if (lasterror != 0)
        LogError("Bluetooth API returned: " + lasterror.ToString());

or

 if (BluetoothSetServiceState(IntPtr.Zero, ref device, ref HumanInterfaceDeviceServiceClass_UUID, BLUETOOTH_SERVICE_ENABLE) != 0)
     LogError("Failed to connect to wiimote controller");

Another Hint

To be more specific, I also already have the code below:

public event EventHandler<EventArgs<string>> Error;

and

ConnectionManager.Error += new EventHandler<EventArgs<string>>(ConnectionManager_Error);

And also this class:

public class EventArgs<T> : EventArgs
{
    public T Value
    {
         get;
         set;
    }

     public EventArgs(T value)
            : base()
     {
        Value = value;
     }
}

Answer 1

Is it standard BeginInvoke that executes code in the separate thread?

You have to work with GUI methods only in GUI thread. To switch to the GUI thread please try Control.IsInvokeRequired and Control.Invoke methods.