My engineering is 450 and I try to choice the goblin engineering.

After accepted the quest in Ironforge which is told going to Gadgetzan, I went to hand in the quest and the problem happended. The goblin did not give me further quest.

I can retake the "Goblin Engineering" quest in the IF over and over, it came to a loop, "start in IF, finish in Gadgetzan".

But the NPC never give me the quest for next step.

Really need help.