diff -r 5ef0ab7b61cd -r a12cca3ad15a lemon/smart_graph.h
--- a/lemon/smart_graph.h	Sun Nov 14 22:48:32 2010 +0100
+++ b/lemon/smart_graph.h	Mon Nov 15 09:46:08 2010 +0100
@@ -1016,7 +1016,7 @@
       return nodes[v._id].partition_index;
     }
     int blueId(Node v) const {
-      LEMON_DEBUG(nodes[v._id].red, "Node has to be blue");
+      LEMON_DEBUG(!nodes[v._id].red, "Node has to be blue");
       return nodes[v._id].partition_index;
     }
     static int id(Arc e) { return e._id; }