diff --git a/tryton/gui/window/view_form/view/graph_gtk/graph.py b/tryton/gui/window/view_form/view/graph_gtk/graph.py
index a854d30ac3..370286739a 100644
--- a/tryton/gui/window/view_form/view/graph_gtk/graph.py
+++ b/tryton/gui/window/view_form/view/graph_gtk/graph.py
@@ -370,7 +370,6 @@ class Graph(Gtk.DrawingArea):
             self.datas.setdefault(x, {})
             for yfield in self.yfields:
                 key = yfield.get('key', yfield['name'])
-                self.datas[x].setdefault(key, 0.0)
                 if yfield.get('domain'):
                     context = rpc.CONTEXT.copy()
                     context['context'] = context.copy()
@@ -379,6 +378,7 @@ class Graph(Gtk.DrawingArea):
                         context[field] = model[field].get(model)
                     if not PYSONDecoder(context).decode(yfield['domain']):
                         continue
+                self.datas[x].setdefault(key, 0.0)
                 if yfield['name'] == '#':
                     self.datas[x][key] += 1
                 else: