title: DTrace on Leopard: No probes specified, even when I specify probes
body: <pre><code>% sudo dtrace -p 2446 'objc$target:NSObject:-init:entry { trace(); }'
  dtrace: no probes specified
  </code></pre>
  
  <p><a href="http://developer.apple.com/documentation/Darwin/Reference/Manpages/man1/dtrace.1.html" rel="nofollow noreferrer">The manpage</a> suggests that this is the correct format with which to specify a probe on an Objective-C method. I tried -Z, but (unsurprisingly) that just didn't print anything.</p>
  
  <p>[Added] It's not even specific to Objective-C probes. I tried it with a C function from AppKit:</p>
  
  <pre><code>sudo dtrace -p 2446 'pid$target::NSPopAutoreleasePool:entry { trace(); }'
  dtrace: no probes specified
  </code></pre>
  
  <p>So what's wrong? Why does DTrace think I have not specified any probes?</p>