ToolstripMenuItem Click raise an error?

Question

Recently added Toolstrip to my C# Application , and there is error when click on menu item that call the function but when call the function from Windowsform Button it works perfect. following is my function:

 private void ShowAddDocument(object sender, EventArgs e)
    {

            foreach (var rr in this.gridEX1.GetDataRows())
            {

                if (rr.Cells["Select"].Value != null)
                {
                    if (rr.Cells["DocumentNumber"].Value.ToString() != "")
                    {

                        rr.BeginEdit();
                        rr.Cells["Select"].Value = null;
                        rr.EndEdit();
                    }
                    else
                    {
                        this.gridEX1.Tag = "SELECTED";


                    }
                }

            }

and I use following line to connect function and Toolstrip MenuItem Click event :

this.userControl11.IssueDocMenuItem.Click += new System.EventHandler(ShowAddDocument);

but when click on Toolstrip Menu Item it raise an error : "Object Reference not set to instance of an object". but strange part is when I use Windowsform Button and call the function by following code:

    private void button1_Click(object sender, EventArgs e)
    {
        ShowAddDocument(sender, e);
    }

It my code works without any error!!!.

Answer 1

I already found behavior named ActAsSelector in my gridex Select Column and set is to True then my problem resolved.happy now.