Added a fix and a unit test for the issue:

#269

The checkin consist of a new test:
Can_Deserialize_Root_Elements_Without_Matching_Case_And_Dashes

Which will deserialze a structure like this:
<incoming-invoices>
<incoming-invoice>
...
<incoming-invoice>
</incoming-invoices>

To a List<IncomingInvoice>

Author: zidad

RestSharp.Tests/SampleClasses/misc.cs

@@ -50,6 +50,11 @@ public class PersonForXml
 		public Disposition Disposition { get; set; }
 
 	}
+    
+    public class IncomingInvoice
+	{
+        public int ConceptId  { get; set; } 
+	}
 
 	public class PersonForJson
 	{

RestSharp.Tests/XmlTests.cs

@@ -464,12 +464,12 @@ public void Can_Deserialize_Names_With_Dashes_On_Default_Root()
 			Assert.NotNull(p.Foes);
 			Assert.Equal(5, p.Foes.Count);
 			Assert.Equal("Yankees", p.Foes.Team);
-		}
-
-		[Fact]
-		public void Can_Deserialize_Names_With_Underscores_Without_Matching_Case_On_Default_Root()
+		}	
+        
+        [Fact]
+		public void Can_Deserialize_Lower_Cased_Root_Elements_With_Dashes()
 		{
-			var doc = CreateLowercaseUnderscoresXml();
+			var doc = CreateDashesXml();
 			var response = new RestResponse { Content = doc };
 
 			var d = new XmlDeserializer();
@@ -497,6 +497,20 @@ public void Can_Deserialize_Names_With_Underscores_Without_Matching_Case_On_Defa
 			Assert.Equal("Yankees", p.Foes.Team);
 		}
 
+		[Fact]
+		public void Can_Deserialize_Root_Elements_Without_Matching_Case_And_Dashes()
+		{
+			var doc = CreateLowerCasedRootElementWithDashesXml();
+			var response = new RestResponse { Content = doc };
+
+			var d = new XmlDeserializer();
+			var p = d.Deserialize<List<IncomingInvoice>>(response);
+
+            Assert.NotNull(p);
+            Assert.Equal(1, p.Count);
+            Assert.Equal(45, p[0].ConceptId);
+		}
+
 
 		[Fact]
 		public void Can_Deserialize_Eventful_Xml()
@@ -726,6 +740,18 @@ private static string CreateDashesXml()
 			doc.Add(root);
 			return doc.ToString();
 		}
+        
+        private static string CreateLowerCasedRootElementWithDashesXml()
+		{
+            var doc = new XDocument();
+			var root = new XElement("incoming-invoices", 
+                new XElement("incoming-invoice", 
+                    new XElement("concept-id", 45)
+                )
+            );
+			doc.Add(root);
+			return doc.ToString();
+		}
 
 		private static string CreateElementsXml()
 		{

RestSharp/Deserializers/XmlDeserializer.cs

@@ -253,12 +253,6 @@ private object HandleListDerivative(object x, XElement root, string propName, Ty
 
 			var name = t.Name;
 
-            if (!elements.Any())
-            {
-                var lowerName = name.ToLower().AsNamespaced(Namespace);
-                elements = root.Descendants().Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == lowerName);
-            } 
-
 			if (!elements.Any())
 			{
 				var lowerName = name.ToLower().AsNamespaced(Namespace);
@@ -274,7 +268,13 @@ private object HandleListDerivative(object x, XElement root, string propName, Ty
 			if (!elements.Any())
 			{
 				elements = root.Descendants().Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == name);
-			}
+			}
+
+            if (!elements.Any())
+            {
+                var lowerName = name.ToLower().AsNamespaced(Namespace);
+                elements = root.Descendants().Where(e => e.Name.LocalName.RemoveUnderscoresAndDashes() == lowerName);
+            } 
 
 			PopulateListFromElements(t, elements, list);