concrete5 BlockView render error

$a = new Area('News Gallery');
$b = Block::getByName('Smugmug Slideshow');
if(is_object($b)) {
  $b->setBlockAreaObject($a);
  $bv = new BlockView();
/*  // this shows the BlockView methods, so it's ok so far...
  $reflect = new ReflectionClass($bv);
  $meths = $reflect->getMethods();
  dump($meths, 'BlockView $bv');
*/
  $bv->render($b);
// Fatal error: Call to a member function cacheBlockRecord() on a non-object in /blah/concrete/models/block.php on line 329
}