Hi Alex,<br><br>There are two lines code in the example "ndn-tree-tracers.cc" like following :<br><br><span style="font-weight: bold;">  ndn::L3AggregateTracer::InstallAll ("aggregate-trace.txt", Seconds (0.5));<br>  ndn::L3RateTracer::InstallAll ("rate-trace.txt", Seconds (0.5));</span><br><br>When I run the scenario successfully, I get two files named "<span style="font-weight: bold;">aggregate-trace.txt</span>" and "<span style="font-weight: bold;">rate-trace.txt</span>".<br>Now, I want to change the file names, so I used the next two lines:<br><br><span style="font-weight: bold;">  ndn::L3AggregateTracer::InstallAll ("xuejin-aggregate-trace.txt", Seconds (0.5));<br>  ndn::L3RateTracer::InstallAll ("xuejin-rate-trace.txt", Seconds (0.5));</span><br><br>But after I run it successfully, the files' names still be<span style="font-weight: bold;"> "</span><span style="font-weight: bold;"><span style="font-weight: bold;">aggregate-trace.txt</span>"</span> and "<span style="font-weight: bold;">rate-trace.txt</span>". Why names can't change?<br><br>Looking forward to your response.<br><br>Jin Xue<br><br>