ViewCellRenderer: Never get into GetCell

Hi
I m using ViewCellRenderer for iOS as below.

`public override UITableViewCell GetCell (Cell item,UITableView tv)
{
var Item = item as CustomViewCell;
tv.SeparatorColor = UIColor.Clear;
var cell = base.GetCell (Item, tv);
cell.SelectionStyle = MonoTouch.UIKit.UITableViewCellSelectionStyle.None;

    return cell;

}`

I never get into GetCell. Please help me out.