After deleting your cache, you should compile your templates (for ezp3.4+) if template compiler is enabled, you can find more about compiling your templates here :
{*by the way you can test your $node here because the error said you are not referencing the $node correctly*}
{$node|attribute(show)}
{*if the code above don´t produce $node information listing, then you are not referencing it right look at yout template space names to reference the $node correctly *}
{section show=ne($node.object.contentclass_id,16)}
{include uri="design:categories_table.tpl"}
{section-else}
{include uri="design:category_listing.tpl"}
{/section}
