plot now not required

common/lib/xmodule/xmodule/gst_module.py

@@ -73,7 +73,9 @@ class GraphicalSliderToolModule(XModule):
         plot_div = '<div class="{element_class}_plot" id="{element_id}_plot" \
                     style="{style}"></div>'
         # extract css style from plot
-        plot_def = re.search(r'\$plot[^\$]*\$', html_string).group()
+        plot_def = re.search(r'\$plot[^\$]*\$', html_string)
+        if plot_def:
+            plot_def = plot_def.group()
             style = re.search(r'(?=.*style\=[\"\'](.*)[\"\'])', plot_def)
             if style:
                 style = style.groups()[0]