diff --git a/ClosedXML/Excel/NamedRanges/XLNamedRanges.cs b/ClosedXML/Excel/NamedRanges/XLNamedRanges.cs
index a7b191f..04d9162 100644
--- a/ClosedXML/Excel/NamedRanges/XLNamedRanges.cs
+++ b/ClosedXML/Excel/NamedRanges/XLNamedRanges.cs
@@ -69,10 +69,16 @@
 
                 if (!match.Success)
                 {
-                    if (Worksheet == null || !XLHelper.NamedRangeReferenceRegex.Match(Worksheet.Range(rangeAddress).ToString()).Success)
-                        throw new ArgumentException("For named ranges in the workbook scope, specify the sheet name in the reference.");
+                    var range = Worksheet.Range(rangeAddress);
+                    if (range == null)
+                        throw new ArgumentException(string.Format("The range address '{0}' for the named range '{1}' is not a valid range.", rangeAddress, rangeName));
                     else
-                        rangeAddress = Worksheet.Range(rangeAddress).ToString();
+                    {
+                        if (Worksheet == null || !XLHelper.NamedRangeReferenceRegex.Match(range.ToString()).Success)
+                            throw new ArgumentException("For named ranges in the workbook scope, specify the sheet name in the reference.");
+                        else
+                            rangeAddress = Worksheet.Range(rangeAddress).ToString();
+                    }
                 }
             }
 
diff --git a/ClosedXML/Excel/XLWorkbook_Load.cs b/ClosedXML/Excel/XLWorkbook_Load.cs
index a23ab4e..192312e 100644
--- a/ClosedXML/Excel/XLWorkbook_Load.cs
+++ b/ClosedXML/Excel/XLWorkbook_Load.cs
@@ -1062,7 +1062,7 @@
                         else
                         {
                             if (!Worksheet(Int32.Parse(localSheetId) + 1).NamedRanges.Any(nr => nr.Name == name))
-                                Worksheet(Int32.Parse(localSheetId) + 1).NamedRanges.Add(name, text, comment).Visible = visible;
+                                (Worksheet(Int32.Parse(localSheetId) + 1).NamedRanges as XLNamedRanges).Add(name, text, comment, true).Visible = visible;
                         }
                     }
                 }
@@ -1073,7 +1073,6 @@
 
         private IEnumerable<String> validateDefinedNames(IEnumerable<String> definedNames)
         {
-            var fixedNames = new List<String>();
             var sb = new StringBuilder();
             foreach (string testName in definedNames)
             {
@@ -2399,4 +2398,4 @@
             return false;
         }
     }
-}
\ No newline at end of file
+}