VertexZ "problem"

in TestCpp example of TMXOrthoVertexZ, i found this message:

 // because I'm lazy, I'm reusing a tile as an sprite, but since this method uses vertexZ, you
 // can use any CCSprite and it will work OK.
CCTMXLayer* layer = map->layerNamed("trees");
 m_tamara = layer->tileAt(ccp(0,11));

So ,i think i can get it work by ccsprite,i change the code like this:

 // because I'm lazy, I'm reusing a tile as an sprite, but since this method uses vertexZ, you
 // can use any CCSprite and it will work OK.
m_tamara = CCSprite::create(s_pPathSister1);
map->addChild(m_tamara);

the result is it does’t work normally, so anyone else can tell how to improve it,tks?