diff --git a/Violin.m b/Violin.m
index 5940f7d..e1c74ca 100644
--- a/Violin.m
+++ b/Violin.m
@@ -115,6 +115,9 @@
             hold('on');
 
             % calculate kernel density estimation for the violin
+            if isempty(data)
+                return
+            end
             [density, value] = ksdensity(data, 'bandwidth', args.Bandwidth);
             density = density(value >= min(data) & value <= max(data));
             value = value(value >= min(data) & value <= max(data));
diff --git a/violinplot.m b/violinplot.m
index c151312..57264f8 100644
--- a/violinplot.m
+++ b/violinplot.m
@@ -85,28 +85,31 @@
             thisData = data.(catnames{n});
             violins(n) = Violin(thisData, n, varargin{:});
         end
-        set(gca, 'xtick', 1:length(catnames), 'xticklabels', catnames);
+        set(gca, 'XTick', 1:length(catnames), 'XTickLabels', catnames);
 
     % 1D data, one category for each data point
     elseif hascategories && numel(data) == numel(cats)
+
         if isempty(grouporder)
             cats = categorical(cats);
         else
             cats = categorical(cats, grouporder);
         end
 
-        catnames = categories(cats);
-        for n=1:length(catnames)
-            thisCat = catnames{n};
+        catnames = (unique(cats)); % this ignores categories without any data
+        catnames_labels = {};
+        for n = 1:length(catnames)
+            thisCat = catnames(n);
+            catnames_labels{n} = char(thisCat);
             thisData = data(cats == thisCat);
             violins(n) = Violin(thisData, n, varargin{:});
         end
-        set(gca, 'xtick', 1:length(catnames), 'xticklabels', catnames);
+        set(gca, 'XTick', 1:length(catnames), 'XTickLabels', catnames_labels);
 
     % 1D data, no categories
     elseif not(hascategories) && isvector(data)
         violins = Violin(data, 1, varargin{:});
-        set(gca, 'xtick', 1);
+        set(gca, 'XTick', 1);
 
     % 2D data with or without categories
     elseif ismatrix(data)
@@ -114,9 +117,9 @@
             thisData = data(:, n);
             violins(n) = Violin(thisData, n, varargin{:});
         end
-        set(gca, 'xtick', 1:size(data, 2));
+        set(gca, 'XTick', 1:size(data, 2));
         if hascategories && length(cats) == size(data, 2)
-            set(gca, 'xticklabels', cats);
+            set(gca, 'XTickLabels', cats);
         end
 
     end