Hi,

the AddRange method does not allow to add a ValueItem with DataValue=null to the collection.
see following example:

ValueList list1 = new ValueList();
list1.ValueListItems.Add(null, null);
list1.ValueListItems.Add("one", "one");
object val1 = list1.ValueListItems[0].DataValue;

ValueList list2 = new ValueList();
ValueListItem[] items = new ValueListItem[2];
items[0] = new ValueListItem(null, null);
items[1] = new ValueListItem("one", "one");
list2.ValueListItems.AddRange(items);
object val2 = list2.ValueListItems[0].DataValue;

val1 = null   is OK
val2 = "ValueListItem0" is a Bug