diff --git a/RhSolutions.AddIn/Controllers/RibbonController.cs b/RhSolutions.AddIn/Controllers/RibbonController.cs
index 4c07779..140ba10 100644
--- a/RhSolutions.AddIn/Controllers/RibbonController.cs
+++ b/RhSolutions.AddIn/Controllers/RibbonController.cs
@@ -27,7 +27,7 @@ public class RibbonController : ExcelRibbon
                 <button id='export' getEnabled='GetExportEnabled' label='Экспорт в новый файл' size='normal' imageMso='PivotExportToExcel' onAction='OnToolPressed'/> 
                 <button id='convert' getEnabled='GetConvertEnabled' label='Актуализировать' size='normal' imageMso='FileUpdate' onAction='OnToolPressed'/> 
                 <button id='merge' label='Объединить' size='normal' imageMso='Copy' onAction='OnToolPressed'/> 
-                <button id='Guessexport' label='Найти и экспортировать' size='normal' imageMso='ControlWizards' onAction='OnToolPressed'/>
+                <button id='Guessexport' getEnabled='GetGuessEnabled' label='Найти и экспортировать' size='normal' imageMso='ControlWizards' onAction='OnToolPressed'/>
                 <button id='dxfexport' getEnabled='GetDxfEnabled' label='Экспортировать в DXF' size='normal' imageMso='ExportExcel' onAction='OnToolPressed'/>
             </group>
             <group id='rausettings' getLabel='GetVersionLabel'>
@@ -117,6 +117,18 @@ public class RibbonController : ExcelRibbon
         }
     }
 
+    public bool GetGuessEnabled(IRibbonControl control)
+    {
+        if (RhSolutionsAddIn.Excel.ActiveWorkbook == null)
+            return false;
+
+        else
+        {
+            Worksheet worksheet = RhSolutionsAddIn.Excel.ActiveWorkbook.ActiveSheet;
+            return !worksheet.IsValidSource();
+        }
+    }
+
     public string GetVersionLabel(IRibbonControl control)
     {
         string version = Assembly.GetExecutingAssembly().GetName().Version.ToString();
diff --git a/RhSolutions.AddIn/Tools/EventsUtil.cs b/RhSolutions.AddIn/Tools/EventsUtil.cs
index afcfd64..92aa717 100644
--- a/RhSolutions.AddIn/Tools/EventsUtil.cs
+++ b/RhSolutions.AddIn/Tools/EventsUtil.cs
@@ -18,8 +18,10 @@ namespace RhSolutions.Tools
             RhSolutionsAddIn.Excel.SheetSelectionChange += RefreshExportButton;
             RhSolutionsAddIn.Excel.SheetActivate += RefreshConvertButton;
             RhSolutionsAddIn.Excel.SheetActivate += RefreshDxfButton;
+            RhSolutionsAddIn.Excel.SheetActivate += RefreshGuessButton;
             RhSolutionsAddIn.Excel.WorkbookActivate += RefreshConvertButton;
             RhSolutionsAddIn.Excel.WorkbookActivate += RefreshDxfButton;
+            RhSolutionsAddIn.Excel.WorkbookActivate += RefreshGuessButton;
             RhSolutionsAddIn.Configuration.OnSettingsChange += RefreshSettingTitle;
         }
 
@@ -28,8 +30,10 @@ namespace RhSolutions.Tools
             RhSolutionsAddIn.Excel.SheetSelectionChange -= RefreshExportButton;
             RhSolutionsAddIn.Excel.SheetActivate -= RefreshConvertButton;
             RhSolutionsAddIn.Excel.SheetActivate -= RefreshDxfButton;
+            RhSolutionsAddIn.Excel.SheetActivate -= RefreshGuessButton;
             RhSolutionsAddIn.Excel.WorkbookActivate -= RefreshConvertButton;
             RhSolutionsAddIn.Excel.WorkbookActivate -= RefreshDxfButton;
+            RhSolutionsAddIn.Excel.WorkbookActivate -= RefreshGuessButton;
             RhSolutionsAddIn.Configuration.OnSettingsChange -= RefreshSettingTitle;
         }
 
@@ -48,6 +52,11 @@ namespace RhSolutions.Tools
             RibbonController.RefreshControl("export");
         }
 
+        private static void RefreshGuessButton(object sh)
+        {
+            RibbonController.RefreshControl("Guessexport");
+        }
+
         private static void RefreshSettingTitle(object sender, SettingChangingEventArgs e)
         {
             RibbonController.RefreshControl("setPriceList");