There are sooo many things which can go wrong...Incorrect creature ID in queststarter table. Incorrect min level. Incorrect class/race restrictions. Creature might be missing quest giver flag... And so on.
You can use this to learn on the blizzard's one and generate some code to create a custom quest.Be careful to not delete any existing ID when you make the sql request.http://keira2.altervista.org/Keira2-dev/#/quest(You can also install keira2 on your server, but if it's just to learn some things, it's not useful)
-- FULL `quest_template_addon` of ID 90000DELETE FROM `quest_template_addon` WHERE (ID = 90000);INSERT INTO `quest_template_addon` (`ID`, `MaxLevel`, `AllowableClasses`, `SourceSpellID`, `PrevQuestID`, `NextQuestID`, `ExclusiveGroup`, `RewardMailTemplateID`, `RewardMailDelay`, `RequiredSkillID`, `RequiredSkillPoints`, `RequiredMinRepFaction`, `RequiredMaxRepFaction`, `RequiredMinRepValue`, `RequiredMaxRepValue`, `ProvidedItemCount`, `SpecialFlags`) VALUES(90000, 0, 0, 0, 63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);-- FULL `quest_request_items` of ID 90000DELETE FROM `quest_request_items` WHERE (ID = 90000);INSERT INTO `quest_request_items` (`ID`, `EmoteOnComplete`, `EmoteOnIncomplete`, `CompletionText`, `VerifiedBuild`) VALUES(90000, 1, 0, 'YOUR_REQUESTITEM_TEXT', 12340);-- FULL `quest_offer_reward` of ID 90000DELETE FROM `quest_offer_reward` WHERE (ID = 90000);INSERT INTO `quest_offer_reward` (`ID`, `Emote1`, `Emote2`, `Emote3`, `Emote4`, `EmoteDelay1`, `EmoteDelay2`, `EmoteDelay3`, `EmoteDelay4`, `RewardText`, `VerifiedBuild`) VALUES(90000, 0, 0, 0, 0, 0, 0, 0, 0, 'YOUR_REWARD_TEXT', 12340);