diff --git a/pdb-js/src/app/plot.service.ts b/pdb-js/src/app/plot.service.ts
index 896b638..5f27aa7 100644
--- a/pdb-js/src/app/plot.service.ts
+++ b/pdb-js/src/app/plot.service.ts
@@ -14,13 +14,13 @@ export class PlotService {
   constructor(private http: HttpClient) {
     this.plotTypes = new Array<PlotType>();
     this.plotTypes.push(new PlotType("SCATTER","Scatter","scatter-chart2",true,DataType.Time,DataType.Duration));
-    this.plotTypes.push(new PlotType("HEATMAP", "Heatmap", "heatmap", false, DataType.Other, DataType.Other));
-    this.plotTypes.push(new PlotType("CONTOUR", "Contour", "contour-chart", false, DataType.Time, DataType.Duration));
     this.plotTypes.push(new PlotType("CUM_DISTRIBUTION", "Cumulative Distribution", "cumulative-distribution-chart", true, DataType.Percent, DataType.Duration));
     this.plotTypes.push(new PlotType("HISTOGRAM", "Histogram", "histogram", true, DataType.HistogramBin, DataType.HistogramCount));
+    this.plotTypes.push(new PlotType("PARALLEL", "Parallel Requests", "parallel-requests-chart", true, DataType.Time, DataType.Count));
+    this.plotTypes.push(new PlotType("HEATMAP", "Heatmap", "heatmap", false, DataType.Other, DataType.Other));
+    this.plotTypes.push(new PlotType("CONTOUR", "Contour", "contour-chart", false, DataType.Time, DataType.Duration));
     this.plotTypes.push(new PlotType("RIDGELINES", "Ridgelines", "ridgelines", false, DataType.Other, DataType.Other));
     this.plotTypes.push(new PlotType("QQ", "Quantile-Quantile", "quantile-quantile", false, DataType.Other, DataType.Other));
-    this.plotTypes.push(new PlotType("PARALLEL", "Parallel Requests", "parallel-requests-chart", true, DataType.Time, DataType.Count));
     this.plotTypes.push(new PlotType("VIOLIN", "Violin", "violin-chart", false, DataType.Group, DataType.Duration));
     this.plotTypes.push(new PlotType("STRIP", "Strip", "strip-chart", false, DataType.Group, DataType.Duration));
     this.plotTypes.push(new PlotType("PIE", "Pie", "pie-chart", false, DataType.Other, DataType.Other));
@@ -92,24 +92,21 @@ export class PlotType {
     this.yAxis = yAxis;
   }
   
-  compatible(other: PlotType) : boolean {
-  
-    const xEqual = this.xAxis === other.xAxis;
-    const yEqual = this.yAxis === other.yAxis;
-    const anyIsOther = this.xAxis === DataType.Other 
-                      || this.yAxis === DataType.Other 
-                      || other.xAxis === DataType.Other 
-                      || other.yAxis === DataType.Other;
-  
-    var result = xEqual || yEqual;
+  compatible(others: Array<PlotType>) : boolean {
+    var result = true;
+    var other : PlotType;
     
-    // if either dimension is Other, then this plot is not compatible with any other plot
-    result = result && !anyIsOther;
-    
-    // is not the same
-    result = result && this.name != other.name;
-    return result;
-  } 
+    var xAxisTypes = new Set([this.xAxis]);
+    var yAxisTypes = new Set([this.yAxis]);
+  
+    for(var i = 0; i < others.length; i++){
+      other = others[i];
+      xAxisTypes.add(other.xAxis);
+      yAxisTypes.add(other.yAxis);
+    }
+  
+    return xAxisTypes.size <= 2 && yAxisTypes.size <= 2;
+  }
 }
 
 export class TagField {
diff --git a/pdb-js/src/app/visualization-page/visualization-page.component.html b/pdb-js/src/app/visualization-page/visualization-page.component.html
index 2dc0d2e..32b665f 100644
--- a/pdb-js/src/app/visualization-page/visualization-page.component.html
+++ b/pdb-js/src/app/visualization-page/visualization-page.component.html
@@ -17,7 +17,7 @@
 
       <mat-form-field>
         <mat-label>Type:</mat-label>
-        <mat-select multiple [(value)]="selectedPlotType">
+        <mat-select multiple [(ngModel)]="selectedPlotType" (ngModelChange)="changePlotType($event)">
           <mat-option *ngFor="let plotType of plotTypes" [value]="plotType">
             <img src="assets/img/{{plotType.icon}}.svg" class="icon-select" /> {{plotType.name}}
           </mat-option>
diff --git a/pdb-js/src/app/visualization-page/visualization-page.component.ts b/pdb-js/src/app/visualization-page/visualization-page.component.ts
index 0d4b3a9..c14da85 100644
--- a/pdb-js/src/app/visualization-page/visualization-page.component.ts
+++ b/pdb-js/src/app/visualization-page/visualization-page.component.ts
@@ -21,7 +21,7 @@ export class VisualizationPageComponent implements OnInit {
   
   dateRange = new FormControl('2019-10-05 00:00:00 - 2019-10-11 23:59:59');
   
-  availablePlotTypes = {};
+  availablePlotTypes = [];
   
   selectedPlotType = [];
   plotTypes: Array<any>;
@@ -65,7 +65,7 @@ export class VisualizationPageComponent implements OnInit {
     this.plotTypes = this.plotService.getPlotTypes();
     this.selectedPlotType.push(this.plotTypes[0]);
     
-    this.plotTypes.forEach(pt => this.availablePlotTypes[pt.name] = pt);
+    this.availablePlotTypes = [].concat(this.plotTypes);
         
     that.plotService.getFilterDefaults().subscribe(function(filterDefaults) {
     
@@ -81,14 +81,12 @@ export class VisualizationPageComponent implements OnInit {
     });
     this.yAxisScale = "LOG10";
   }
-    
-  getCombinablePlotTypes(selectedMainPlotType) : Array<any>{
-      //const mainPlotType = this.availablePlotTypes[selectedMainPlotType];
-      const mainPlotType = selectedMainPlotType;
-      
-      const compatiblePlotTypes = this.plotTypes.filter(pt => pt.compatible(mainPlotType));
-      return compatiblePlotTypes;
+  
+  changePlotType(selectedPlotTypes: Array<PlotType>) {
+    const compatiblePlotTypes = this.availablePlotTypes.filter(pt => pt.compatible(selectedPlotTypes));
+    this.plotTypes = compatiblePlotTypes;
   }
+   
   
   dateRangeAsString() : string {
     return (<HTMLInputElement>document.getElementById("search-date-range")).value;
diff --git a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/AggregateHandlerCollection.java b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/AggregateHandlerCollection.java
index ed2071e..37084e1 100644
--- a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/AggregateHandlerCollection.java
+++ b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/AggregateHandlerCollection.java
@@ -45,7 +45,10 @@ public class AggregateHandlerCollection {
                     // TODO merge axis definitions and use the greater values for: range,
                     // ticsIncrement
                 } else {
-                    Preconditions.checkSmaller(result.size(), 2, "at most two different axis are supported");
+                    Preconditions.checkSmaller(result.size(), 2,
+                            "At most two different axis are supported. "
+                                    + "The combination of plot types needs more than two " + axis
+                                    + "-axis. Remove one or more plot types.");
                     final GnuplotAxis mirrorAxis = axis.mirrorAxis();
                     handler.updateAxis(mirrorAxis);
                     result.add(type);