I am reading values from a selected textfile and then displaying them in a textbox present on my Windows.Form. After my whole textfile has been looped through, the last line in my textfile is repeated again and then I receive the error message: "Exception: Index out of array range."

Do you know what I could have done wrong in my loop?

Code:
        protected void ReadFile()
        {
            try
            {
                String line = null;
                using (mStreamReader = File.OpenText(mOpenFileDialog.FileName))
                {
                    while ((line = mStreamReader.ReadLine()) != null)
                    {
                        SplitLine(line);
                        ConvertToLong();
                    }
                }
                tbxDisplay.Text = msContents;
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message);
            }
        }