Shadedstar

Hello. I have a problem with turning in a quest that is the last one in a chain, caleed The Missing Diplomat. When I turned in the previous to last quest, it said in chat that I accepted the last quest. A golden question mark appeared atop of Jaina, but when I talk to her, there's no quest window to complete it. ALSO, there is no quest in my quest log. There's a blue questionmark on a nearby NPC with a quest window, but nothing happens when I hit Complete quest. How do I complete it?

Tried to do what you said, sadly no result.