--- a/ckanext/ga_report/controller.py
+++ b/ckanext/ga_report/controller.py
@@ -417,11 +417,14 @@
     # Create a consistent x-axis between all series
     num_points = [ len(series['data']) for series in data ]
     ideal_index = num_points.index( max(num_points) )
-    x_axis = [ point['x'] for point in data[ideal_index]['data'] ]
+    x_axis = []
+    for series in data:
+        for point in series['data']:
+            x_axis.append(point['x'])
+    x_axis = sorted( list( set(x_axis) ) )
+    # Zero pad any missing values
     for series in data:
         xs = [ point['x'] for point in series['data'] ]
-        assert set(xs).issubset( set(x_axis) ), (xs, x_axis)
-        # Zero pad any missing values
         for x in set(x_axis).difference(set(xs)):
             series['data'].append( {'x':x, 'y':0} )
     if percentageMode:
@@ -430,9 +433,6 @@
             for series in series_list:
                 for point in series['data']:
                     totals[point['x']] = totals.get(point['x'],0) + point['y']
-            lengths = [ len(series['data']) for series in series_list ]
-            assert len(set(lengths))==1
-            assert lengths[0] == len(totals)
             return totals
         # Transform data into percentage stacks
         totals = get_totals(data)

--- a/ckanext/ga_report/public/css/ga_report.css
+++ b/ckanext/ga_report/public/css/ga_report.css
@@ -18,6 +18,7 @@
 .rickshaw_legend {
   background: transparent;
   width: 100%;
+  padding-top: 4px;
 }
 .rickshaw_y_axis {
   position: absolute;
@@ -29,6 +30,10 @@
   background: transparent !important;
   color: #000000 !important;
   font-weight: normal !important;
+}
+.rickshaw_legend .instructions {
+  color: #000;
+  margin-bottom: 6px;
 }
 
 .rickshaw_legend .line .action {
@@ -44,6 +49,9 @@
   float: left;
   width: 200px;
 }
+.rickshaw_legend .line .label:hover {
+  text-decoration: underline;
+}
 
 .ga-reports-table .td-numeric {
   text-align: center;

--- a/ckanext/ga_report/public/scripts/ckanext_ga_reports.js
+++ b/ckanext/ga_report/public/scripts/ckanext_ga_reports.js
@@ -45,6 +45,7 @@
       graph: graph,
       legend: legend
     } );
+    myLegend.prepend('<div class="instructions">Click on a series below to isolate its graph:</div>');
     graph.render();
 };
 
@@ -94,6 +95,7 @@
       }
       legend_name = '#legend_'+legend_name;
       $('#graph-legend-container > *').hide();
+      $('#graph-legend-container .instructions').show();
       $(legend_name).show();
     }
   );