I'm guessing you just got to Kaineng and thought you'd be able to wander into Raisu Palace? Not so. You need to play through the game first. Raisu Palace is the penultimate mission, and the mission following Unwaking Waters. Don't concern yourself with trying to get into Raisu Palace just now.
If you have completed Unwaking Waters it is likely you did not take the next quest. If you can reach the Harvest Temple go there, and speak to Kuunavang (the dragon) to take the quest to go to Raisu Palace.
Minister Cho's Estate
Zen Daijun
Vizunah Square
Nahpui Quarter
Tannahkai Temple
Arborstone
Boreas Seabed
Sunjiang District
Eternal Grove/Gyala Hatchery
Unwaking Waters
Raisu Palace
Imperial Sanctum
Missions go in that order. Can't do Raisu until you did Unwaking Waters, as was stated. Make sure you did all the missions and taken the primary quest from Kuunavang after completing Unwaking Waters.