DayPilot:DayPilotScheduler bug?

You need to modify the event handler as follows:

protected void DayPilotScheduler1_BeforeResHeaderRender(object sender, BeforeResHeaderRenderEventArgs e)
  {
  DataItemWrapper task = e.DataItem;
  int duration = Convert.ToInt32(task["Days"]);
  if (DayPilotScheduler1.IsExport) {
    e.Columns[0].InnerHTML = duration + " 天";
  }
  else {
    e.Columns[0].InnerHTML = <div style='text-align:right; padding: 0px 6px 0px 2px;'>" + duration + " 天</div>";
  }
}

See also:
http://kb.daypilot.org/86539/events-show-html-source-during-image-export-png/