diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
index 67d4c6b..11a3bfb 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/Cells/XLCell.cs
@@ -590,7 +590,8 @@
                 //    val = baseDate.Add(timeSpan).ToOADate().ToString();
                 //}
                 dataType = XLCellValues.TimeSpan;
-                Style.NumberFormat.NumberFormatId = 46;
+                if (Style.NumberFormat.Format == String.Empty && Style.NumberFormat.NumberFormatId == 0)
+                    Style.NumberFormat.NumberFormatId = 46;
             }
             else if (Double.TryParse(val, out dTest))
             {
@@ -600,10 +601,11 @@
             {
                 dataType = XLCellValues.DateTime;
 
-                if (dtTest.Date == dtTest)
-                    Style.NumberFormat.NumberFormatId = 14;
-                else
-                    Style.NumberFormat.NumberFormatId = 22;
+                if (Style.NumberFormat.Format == String.Empty && Style.NumberFormat.NumberFormatId == 0)
+                    if (dtTest.Date == dtTest)
+                        Style.NumberFormat.NumberFormatId = 14;
+                    else
+                        Style.NumberFormat.NumberFormatId = 22;
 
                 val = dtTest.ToOADate().ToString();
             }
diff --git a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
index deff59e..3d1eaad 100644
--- a/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
+++ b/ClosedXML/ClosedXML/ClosedXML/Excel/XLWorkbook_Save.cs
@@ -625,8 +625,8 @@
                 workbook.WorkbookProperties.DefaultThemeVersion = (UInt32Value)124226U;
             #endregion
 
-            //if (workbook.BookViews == null)
-            //    workbook.BookViews = new BookViews();
+            if (workbook.BookViews == null)
+                workbook.BookViews = new BookViews();
 
             if (workbook.Sheets == null)
                 workbook.Sheets = new Sheets();
@@ -671,29 +671,29 @@
                                 orderby worksheet.Position
                                 select sheet;
 
-            //UInt32 firstSheetVisible = 0;
+            UInt32 firstSheetVisible = 0;
 
-            //foreach (var sheet in sheetElements)
-            //{
-            //    workbook.Sheets.RemoveChild(sheet);
-            //    workbook.Sheets.Append(sheet);
-            //    if (firstSheetVisible == 0 && sheet.State != null && sheet.State != SheetStateValues.Visible)
-            //        firstSheetVisible++;
-            //}
+            foreach (var sheet in sheetElements)
+            {
+                workbook.Sheets.RemoveChild(sheet);
+                workbook.Sheets.Append(sheet);
+                if (firstSheetVisible == 0 && sheet.State != null && sheet.State != SheetStateValues.Visible)
+                    firstSheetVisible++;
+            }
 
-            //WorkbookView workbookView = workbook.BookViews.Elements<WorkbookView>().FirstOrDefault();
+            WorkbookView workbookView = workbook.BookViews.Elements<WorkbookView>().FirstOrDefault();
 
 
-            //if (workbookView == null)
-            //{
-            //    workbookView = new WorkbookView() { ActiveTab = firstSheetVisible, FirstSheet = firstSheetVisible };
-            //    workbook.BookViews.Append(workbookView);
-            //}
-            //else
-            //{
-            //    workbookView.ActiveTab = firstSheetVisible;
-            //    workbookView.FirstSheet = firstSheetVisible;
-            //}
+            if (workbookView == null)
+            {
+                workbookView = new WorkbookView() { ActiveTab = firstSheetVisible, FirstSheet = firstSheetVisible };
+                workbook.BookViews.Append(workbookView);
+            }
+            else
+            {
+                workbookView.ActiveTab = firstSheetVisible;
+                workbookView.FirstSheet = firstSheetVisible;
+            }
             
 
             DefinedNames definedNames = new DefinedNames();
diff --git a/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/HideSheets.cs b/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/HideSheets.cs
index 25c3bfd..b605355 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/HideSheets.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Examples/Misc/HideSheets.cs
@@ -47,11 +47,12 @@
         public void Create(String filePath)
         {
             var wb = new XLWorkbook();
-
+            
+            wb.Worksheets.Add("First Hidden").Hide();
             wb.Worksheets.Add("Visible");
-            wb.Worksheets.Add("Hidden").Hide();
             wb.Worksheets.Add("Unhidden").Hide().Unhide();
             wb.Worksheets.Add("VeryHidden").Visibility = XLWorksheetVisibility.VeryHidden;
+            wb.Worksheets.Add("Last Hidden").Hide();
 
             wb.SaveAs(filePath);
         }
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
index c3f439f..f0dc88e 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
@@ -15,12 +15,14 @@
 
         static void Main(string[] args)
         {
-            var fileName = "Issue_6295";
+            //var fileName = "Issue_6313";
             //var fileName = "Blank";
-            //var fileName = "Sandbox";
-            var wb = new XLWorkbook(String.Format(@"c:\Excel Files\ForTesting\{0}.xlsx", fileName));
-            //var wb = new XLWorkbook();
-            
+            var fileName = "Sandbox";
+            //var wb = new XLWorkbook(String.Format(@"c:\Excel Files\ForTesting\{0}.xlsx", fileName));
+            var wb = new XLWorkbook();
+
+            wb.Worksheets.Add("Hidden").Hide();
+            wb.Worksheets.Add("Unhidden").Hide().Unhide();
 
             wb.SaveAs(String.Format(@"c:\Excel Files\ForTesting\{0}_Saved.xlsx", fileName));
         }
@@ -100,12 +102,15 @@
                 foreach (var i in Enumerable.Range(1, 1))
                 {
                     var ws = wb.Worksheets.Add("Sheet" + i);
-                    foreach (var ro in Enumerable.Range(1, 50))
+                    foreach (var ro in Enumerable.Range(1, 200))
                     {
-                        foreach (var co in Enumerable.Range(1, 50))
+                        foreach (var co in Enumerable.Range(1, 200))
                         {
                             ws.Cell(ro, co).Style = GetRandomStyle();
-                            ws.Cell(ro, co).Value = GetRandomValue();
+                            //if (rnd.Next(1, 5) == 1)
+                                ws.Cell(ro, co).FormulaA1 = ws.Cell(ro + 1, co + 1).Address.ToString() + " & \"-Copy\"";
+                            //else
+                            //    ws.Cell(ro, co).Value = GetRandomValue();
                         }
                         //System.Threading.Thread.Sleep(10);
                     }
@@ -223,7 +228,7 @@
                 return DateTime.Now;
             else if (val == 5)
                 return rnd.Next(1, 1000);
-            else
+            else 
                 return (DateTime.Now - baseDate);
         }