Here is my class:

public class Command
{
   [XmlArray(IsNullable = true)]
   public List<Parameter> To { get; set; }
}

When I serialize an object of this class:

var s = new XmlSerializer(typeof(Command));
s.Serialize(Console.Out, new Command());

it prints as expected (xml header and default MS namespaces are omitted):

<Command><To xsi:nil="true" /></Command>

When I took this xml and tried to deserialize it I got stucked, because it always print "Not null":

var t = s.Deserialize(...);
if (t.To == null)
    Console.WriteLine("Null");
else
    Console.WriteLine("Not null");

How to force deserializer to make my list null, if it is null in xml?