need help with datamapper orm and nestedsets

[eluser]kev[/eluser]
Anybody know what's causing this?

This is the new code im using..

Code:

$root = new Category();
  $root->get_root(); // get the root
  
  $obj = new Category();
  $obj->get_root();

  echo $root->dump_tree( $obj, array('title'), 'html' , true );

It's echoing Array instead of html output.