I make sure I've installed all correctly and it had worked after that but today, when I replace a new phpbb_seo_class.php , I cannot see Zerodup & Nodupe options. I have reinstalled no dupe and zero dupe in only file phpbb_seo_class.php and afterthat, purge cache, and I still not see zerodup & nodupe! Can you help me

Make sure you did not forget anything in your phpbb_seo_class.php file. It's normal to see these go away from the acp if you updated without maintaining their code in phpbb_seo_class.php at first, but they should should up again as soon as you put the code back in phpbb_seo_class.php.

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Oh! I have seen it again , thank you so much & thanks for your mod