在msce中画的电缆，怎么通过电缆的ID通过编码获取电缆的体积和表面积。

DgnModel dgnModel = Session.Instance.GetActiveDgnModel();
Element myElem = dgnModel.FindElementById((ElementId)1513L); 
if (null == myElem)
{
    MessageCenter.Instance.ShowInfoMessage("Can't find element which id=1513", null, true);
    return;
}
DgnFile dgnFile = Session.Instance.GetActiveDgnFile();
ECSchema baseSchema = DgnECManager.Manager.LocateDeliveredSchema("BaseElementSchema", 1, 0, SchemaMatchType.LatestCompatible, dgnFile) as ECSchema;
ECClass volClass = baseSchema.GetClass("MstnVolume") as ECClass;
IDgnECInstance inst = DgnECManager.FindECInstanceOnElement(myElem, volClass);
            
string msg = "SurfaceArea = " + inst["SurfaceArea"].StringValue + ", Volume = " + inst["Volume"].StringValue;
MessageCenter.Instance.ShowInfoMessage(msg, null, true);