diff --git a/mindplot/src/main/javascript/FixedDistanceBoard.js b/mindplot/src/main/javascript/FixedDistanceBoard.js
index a99862c7..db7927c1 100644
--- a/mindplot/src/main/javascript/FixedDistanceBoard.js
+++ b/mindplot/src/main/javascript/FixedDistanceBoard.js
@@ -81,15 +81,17 @@ mindplot.FixedDistanceBoard.prototype.updateReferencePoint = function()
     {
         var entry = entries[i];
 
-        var upperLimit = entry.getUpperLimit() + yOffset;
-        var lowerLimit = entry.getLowerLimit() + yOffset;
-        entry.setUpperLimit(upperLimit);
-        entry.setLowerLimit(lowerLimit);
+        if(core.Utils.isDefined(entry)){
+            var upperLimit = entry.getUpperLimit() + yOffset;
+            var lowerLimit = entry.getLowerLimit() + yOffset;
+            entry.setUpperLimit(upperLimit);
+            entry.setLowerLimit(lowerLimit);
 
-        // Fix x position ...
-        var xPos = this.workoutXBorderDistance();
-        entry.setXPosition(xPos);
-        entry.update();
+            // Fix x position ...
+            var xPos = this.workoutXBorderDistance();
+            entry.setXPosition(xPos);
+            entry.update();
+        }
     }
     this._referencePoint = parentPosition.clone();
 
diff --git a/mindplot/src/main/javascript/MindmapDesigner.js b/mindplot/src/main/javascript/MindmapDesigner.js
index fbece68c..6043952a 100644
--- a/mindplot/src/main/javascript/MindmapDesigner.js
+++ b/mindplot/src/main/javascript/MindmapDesigner.js
@@ -574,7 +574,8 @@ mindplot.MindmapDesigner.prototype._nodeModelToNodeGraph = function(nodeModel)
     for (var i = 0; i < children.length; i++)
     {
         var child = children[i];
-        this._nodeModelToNodeGraph(children[i]);
+        if(core.Utils.isDefined(child))
+            this._nodeModelToNodeGraph(child);
     }
 
     var workspace = this._workspace;