else if (IsDateTime(v))
					{
						switch(sop)
						{
							case SOP_MIN:
								if (((Date) v) < ((Date) t))
									t = v;
								break;
							case SOP_MAX:
								if (((Date) v) > ((Date) t))
									t = v;
								break;
							case SOP_SUM:
							case SOP_AVG:
								t = v;
								break;
						}
					}