Puzzled about Subcategories extension

starlucent

I'm a real vanilla newbie, and am trying to set up my first forum with some test posts today. I've installed the subcategories extension, and would like to follow the instructions in the readme file, but when I amend the categories.php file as instructed, upload it and then visit the categories page, I get a blank page (just white). I've inserted this: $CategoryList .= ' <li class="CategoryDiscussionCount"> <span>'.$this->Context->GetDefinition('SubCategories').'</span> '.SubCategoryCount($Category->CategoryID).' </li>'; immediately after: <li class="CategoryDiscussionCount"> <span>'.$this->Context->GetDefinition('Discussions').'</span> '.$Category->DiscussionCount.' </li>'; and before: if ($Category->Blocked) { $CategoryList .= '<a id="BlockCategory'.$Category->CategoryID.'" onclick="ToggleCategoryBlock('."'".$this->Context->Configuration['WEB_ROOT']."ajax/blockcategory.php', ".$Category->CategoryID.", 0, 'BlockCategory".$Category->CategoryID."', '".$SessionPostBackKey."');\">".$this->Context->GetDefinition('UnblockCategory').'</a>'; else ..... Have I misunderstood where this chunk of code is to go? Am I missing something? Should I be uploading the revised version into the forum subdirectory or the themes subdirectory? I'm getting confused ... Please help if you can. Thanks