--- a/pvl/verkko/rrd.py	Sun Jan 20 18:26:54 2013 +0200
+++ b/pvl/verkko/rrd.py	Sun Jan 20 18:31:21 2013 +0200
@@ -20,6 +20,9 @@
     """
 
     def __init__ (self, path) :
+        if not path :
+            raise ValueError("RRDDatabase: no path given")
+
         log.info("%s", path)
 
         self._path = path
@@ -218,7 +221,7 @@
         graph_url = self.url(Graph, tree=self.tree, target=rrd)
         
         return html.a(href=target_url)(
-                html.p(rrd),
+                html.h3(rrd),
                 html.img(src=graph_url),
         )