Usually there are reasons to why your appeal gets denied, lack of information, badly written appeal, various other reasons though really depends on the appeal itself. But to why your appeal was denied isn't something I can comment on as I didn't handle your appeal.
Though if you wish to discuss your appeal/ban further, then I suggest you email
sentinelteam@cubecraft.net about your ban and besure to include information such as your username, platform you were banned on and various other information such as mods/clients, what you were doing in the moments leading to your ban etc.