--- a/src/network/examples/main-packet-header.cc	Tue May 15 15:53:20 2012 +0100
+++ b/src/network/examples/main-packet-header.cc	Tue May 15 16:02:26 2012 -0700
@@ -100,6 +100,9 @@
 
 int main (int argc, char *argv[])
 {
+  // Enable the packet printing through Packet::Print command.
+  Packet::EnablePrinting ();
+
   // instantiate a header.
   MyHeader sourceHeader;
   sourceHeader.SetData (2);