What could stop a component appearing on the front end? I'm new to Drupal and have been given a task beyond my knowledge.

I am trying to transfer a component (simple image gallery) from one site to another. I've simply copied the component files (.tpl, .module, .inc) into the new site's equivalent directories.

The back-end appears fine: I can add the component to a Panel and adjust its settings. I've replicated exactly what was on the previous site. But nothing appears on the front end.

I've tried clearing the cache and rebuilding the registry, of course. 

Would anyone know what file/function I should be looking at to get this working?
In this instance it was an error in the component's render function

gallery_grid_render($subtype, $conf, $args, $contexts) {


where it was returning the information to the block.

$block-&gt;content = theme('this_name_was_wrong', $tpl_vars);