I am facing the same problems too.
1st - After I reached lvl 15, I went to find Sin npc, and searched for quest to be done, he/she has no quest for me to be done.
2nd - I went to hidden klang valley, find that super hero standing at the top of the mountain, named Dong Gwa, and I tried talk to him, I couldnt talk to him.
So, how to settle these quests when I couldnt receive the tasks or talk to them?