null Delegate/event

[Dave Sell]

All,

Can you help? I am kinda new to C#, a long-time VB guy.

I have nearly identical code in another project, but this code (kinda copied-pasted) is not working.

The event "MyDataChanged" is always null when I try to call it. Cannot figure out why?

Thanks!

Dave

namespace OPC_Process_Driver
{
    public partial class frmMain : Form
    {
        private OPC_Process.cls_OPC_Group m_OPC_Process;

        // dhs - added delegate for VB Event consumption
        public delegate void theDataChanged(object source, string strContext, string strTagName, string strTagValue);
        public event theDataChanged MyDataChanged;
        public void NotifyDataChanged(string strContext, string strTagName, string strTagValue)
        {
            if (MyDataChanged != null)
            {
                MyDataChanged(this, strContext, strTagName, strTagValue);
                // THIS IS ALWAYS NULL!!!            }
        }

        public frmMain()
        {
            InitializeComponent();
            m_OPC_Process = new cls_OPC_Group();
            m_OPC_Process.DataChanged += new __cls_OPC_Group_DataChangedEventHandler(this.HandleDataChanged);
        }
        private void HandleDataChanged(ref string Context, ref string TagName, ref string TagValue)
        {
            // Handle the event
            this.NotifyDataChanged(Context, TagName, TagValue); 
        }

        private void btn_TestDataChanged_Click(object sender, EventArgs e)
        {
            NotifyDataChanged("Context", "TagName", "TagValue");
        }

        private void btn_InitOPC_Click(object sender, EventArgs e)
        {
            string server, context, refresh;
            server = "SWToolbox.TOPServer";
            context = "Channel_1";
            refresh = "100";
            m_OPC_Process.Initialize_OPC(ref server, ref context, ref refresh);
        }

        private void btn_AddItem_Click(object sender, EventArgs e)
        {
            string context, tagname;
            context = "Channel_1";
            tagname = "Device_1.HeartBeat";
            m_OPC_Process.AddListener(ref context, ref tagname);
        }


    }
}

I'm trying to do something like this but it won't compile:

        public frmMain()
        {
            InitializeComponent();
            m_OPC_Process = new cls_OPC_Group();
            m_OPC_Process.DataChanged += new __cls_OPC_Group_DataChangedEventHandler(this.HandleDataChanged);
             this.MyDataChanged += new System.EventHandler(MyDataChanged);        
}

[Dave Sell]

OK I was able to get past this using this code:

        public frmMain()
        {
            InitializeComponent();
            m_OPC_Process = new cls_OPC_Group();
            m_OPC_Process.DataChanged += new __cls_OPC_Group_DataChangedEventHandler(this.HandleDataChanged);
            this.MyDataChanged += new theDataChanged(frmMain_MyDataChanged);
        }

        private void frmMain_MyDataChanged(object source, string strContext, string strTagName, string strTagValue)
        {
            this.Text = strTagValue;
        }