How to use PathCamera?

Sorry I'm a absolute newbie, I just tried to use PathCamera, but it didn't work, can anyone tell me why?

Here is my pathCamera.cs (I modified it from pathShape.cs):

datablock PathCameraData( MyPathCamera )
{
   mode = "";
};

function MyPathCamera::onAdd(%this, %obj)
{
}

function MyPathCamera::onNode(%this, %camera, %node)
{
}

function PathCamera::followPath(%this, %path)
{
   %this.path = %path;
   
   if (!(%this.speed = %path.speed))
      %this.speed = 100;
      
   if (%path.isLooping)
      %this.loopNode = %path.getCount() - 2;
   else
      %this.loopNode = -1;
   
   %this.pushPath(%path);   
   %this.popFront();
}

function PathCamera::pushPath(%this, %path)
{
   for (%i = 0; %i < %path.getCount(); %i++)
      %this.pushNode(%path.getObject(%i));
}

function PathCamera::pushNode(%this, %node)
{
   if (!(%speed = %node.speed))
      %speed = %this.speed;
      
   if ((%type = %node.type) $= "")
      %type = "Normal";
      
   if ((%smoothing = %node.smoothing) $= "")
      %smoothing = "Linear";
      
   %this.pushBack(%node.getTransform(), %speed, %type, %smoothing);
}

Then I modified the function onClientEnterGame:

function GameConnection::onClientEnterGame(%this)
{
   // Every client get's a camera object.
   %this.camera = new PathCamera()
   {
      dataBlock = MyPathCamera;
   };
   
   %this.camera.followPath("MissionGroup/CameraPath");
   MissionCleanup.add( %this.camera );
   %this.camera.scopeToClient(%this);

   // Create a player object.
   %spawnPoint = pickSpawnPoint();
   %this.createPlayer(%spawnPoint);
}

When I ran the demo, nothing happened! Can anybody help me with this? I really appreciate your help! Thanks a lot!