diff --git a/Chart/BarChart.js b/Chart/BarChart.js
index 774f871..6aeb58c 100644
--- a/Chart/BarChart.js
+++ b/Chart/BarChart.js
@@ -111,10 +111,13 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
 
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
+
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
+        
         this.chart.drawMarker(svg, x, y, dataPointEnter, dataPoint);
         this.chart.drawLegend(svg, dataPointEnter, dataPoint);
         this.chart.drawText(svg);
diff --git a/Chart/ChartAbstract.js b/Chart/ChartAbstract.js
index 5ad589e..0a9de3c 100644
--- a/Chart/ChartAbstract.js
+++ b/Chart/ChartAbstract.js
@@ -315,6 +315,8 @@
         }
 
         if (this.dataSettings.info.visible && this.dataSettings.marker.visible) {
+            temp = dataPointEnter.append('g').attr('class', 'dots');
+
             let div = this.chartSelect.append("div").attr("class", "charttooltip").style("opacity", 0);
             div.html(self.axis.x.label.text + ': ' + 100 + "<br/>" + self.axis.y.label.text + ': ' + 100);
 
diff --git a/Chart/ColumnChart.js b/Chart/ColumnChart.js
index 216999b..3133b21 100644
--- a/Chart/ColumnChart.js
+++ b/Chart/ColumnChart.js
@@ -111,7 +111,8 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
 
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
@@ -206,6 +207,7 @@
     {
         y.domain([yMin, yMax]);
 
+        // todo: n is undefined !!!!
         rect.transition()
             .duration(500)
             .delay(function (d, i)
diff --git a/Chart/LineChart.js b/Chart/LineChart.js
index e96fbd3..b06c5cd 100644
--- a/Chart/LineChart.js
+++ b/Chart/LineChart.js
@@ -127,6 +127,8 @@
             {
                 return y(d.y);
             });
+        } else {
+            return;
         }
 
         zoom = d3.behavior.zoom().x(x).scaleExtent([1, 2]).on('zoom', function ()
@@ -190,10 +192,13 @@
         //svg.selectAll('.x.axis').transition().duration(500).call(xAxis1);
         //svg.selectAll('.y.axis').transition().duration(500).call(yAxis1);
 
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, line, dataPointEnter, dataPoint);
+
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
+
         this.chart.drawMarker(svg, x, y, dataPointEnter, dataPoint);
         this.chart.drawLegend(svg, dataPointEnter, dataPoint);
         this.chart.drawText(svg);
diff --git a/Chart/PieChart.js b/Chart/PieChart.js
index a7437d2..5599cd9 100644
--- a/Chart/PieChart.js
+++ b/Chart/PieChart.js
@@ -33,7 +33,8 @@
                 + (this.chart.margin.left) + ","
                 + (this.chart.margin.top) + ")");
 
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
diff --git a/Chart/PyramidChart.js b/Chart/PyramidChart.js
index 10ae00d..0a7060a 100644
--- a/Chart/PyramidChart.js
+++ b/Chart/PyramidChart.js
@@ -145,7 +145,8 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
         
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
diff --git a/Chart/ScatterplotChart.js b/Chart/ScatterplotChart.js
index 7c994da..5aa591a 100644
--- a/Chart/ScatterplotChart.js
+++ b/Chart/ScatterplotChart.js
@@ -91,7 +91,8 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
         
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
diff --git a/Chart/VWaterfallChart.js b/Chart/VWaterfallChart.js
index b0afe45..d0232a4 100644
--- a/Chart/VWaterfallChart.js
+++ b/Chart/VWaterfallChart.js
@@ -103,7 +103,8 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
         
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];
diff --git a/Chart/WaterfallChart.js b/Chart/WaterfallChart.js
index a99dcad..67621c2 100644
--- a/Chart/WaterfallChart.js
+++ b/Chart/WaterfallChart.js
@@ -103,7 +103,8 @@
 
         this.chart.drawGrid(svg, xGrid, yGrid);
         
-        let dataPoint, dataPointEnter,
+        let dataPoint = null, 
+            dataPointEnter = null,
             temp       = this.drawData(svg, x, y, dataPointEnter, dataPoint);
         dataPointEnter = temp[0];
         dataPoint      = temp[1];