Linecount not increasing in Iwpftextview while word wrap enabled

Hello Friends,

I am using IWpfTextView and want to show vertical scrollbar in textbuffer(whenever required)

Here is my code

private void SetScrollBarVisibilty()
        {

IWpfTextViewMargin verticalScrollBar = wpfTextViewHost.GetTextViewMargin(PredefinedMarginNames.VerticalScrollBar) as IWpfTextViewMargin;
            if (verticalScrollBar != null)
            {
                double actuaWidth = ((((wpfTextViewHost.TextView).TextViewLines).LastVisibleLine).VisibleArea.Height / wpfTextView.LineHeight);
                char lasstChar = new char();
                if (this.Text != string.Empty)
                    lasstChar = this.Text.Last();
                if ((actuaWidth <= textBuffer.CurrentSnapshot.LineCount) ||
                   (Math.Truncate(actuaWidth) <= (wpfTextViewHost.TextView).TextViewLines.Count) ||
                   (Math.Truncate(actuaWidth) <= (wpfTextViewHost.TextView).TextViewLines.Count && lasstChar.Equals('\n')))
                {
                    verticalScrollBar.VisualElement.Visibility = System.Windows.Visibility.Visible;
                }
                else if (verticalScrollBar.VisualElement.Visibility == System.Windows.Visibility.Visible && actuaWidth > textBuffer.CurrentSnapshot.LineCount)
                    verticalScrollBar.VisualElement.Visibility = System.Windows.Visibility.Collapsed;
            }