diff --git a/scripts/logsheet.js b/scripts/logsheet.js
index d1ff713..4e476c3 100644
--- a/scripts/logsheet.js
+++ b/scripts/logsheet.js
@@ -294,15 +294,19 @@
     aggBy.total = function (sheet_id, sheet, attribute) {
         if (!(sheet_id in floGlobals.appObjects.logSheet.sheetList))
             throw ("Sheet not found")
-        let result = 0;
+        let result = 0, count = 0;
         let attrubuteIndex = floGlobals.appObjects.logSheet.sheetList[sheet_id].attributes.indexOf(attribute)
         sheet.forEach(l => {
             if (!_isNaN(l.log[attrubuteIndex])) {
                 let value = parseFloat(l.log[attrubuteIndex])
                 result += value;
+                count++;
             }
         });
 
+        if (count == 0)
+            result = null;
+
         return result;
     }
 
@@ -318,7 +322,10 @@
                 count++;
             }
         })
-        result = result / count;
+        if (count == 0)
+            result = null;
+        else
+            result = result / count;
         return result;
     }