How do I execute a probe only if a certain data condition is met?

probe thread
{
  probe "outer_routine"
  {
    // Note that this probe has a name "InnerProbe"
    probe "inner_routine"
    {
      ; // Inner routine stuff
    } InnerProbe;

    // Entry to outer_routine
    on_entry
    {
      if ($param1 == 3)
      {
        // We can enable or disable the probe
        ap_EnableProbe (InnerProbe);
      }
      else
      {
        // Disable the inner probe
       ap_DisableProbe (InnerProbe);
      }
    }
  }
}