Add property into cutlist item error

[Brent-bai]

var drwNoName = "DrawingNo";
var item = cutListItem.Properties.GetOrPreCreate(drwNoName);
  item.Value = PartNo + "-" + (i + 1).ToString();
  if (!item.IsCommitted)
      item.Commit();

"item.Value =..." in above code occure error: "System.Exception:“Failed to set the value of the property 'DrawingNo'. Error code: swCustomInfoSetResult_NotPresent”", and the "item.Value = null".