Is that what it takes to get it to work - to go directly from France to China? You can't do that without Traveler. You have to send them to their home world and let them rest a couple of days before they can travel anywhere again. I have a bunch of Twallan's mods already, what's one more? But I'm getting awfully tired of trying to complete that one cave. My sim's on her fourth trip to China, and has already spent 36 days there on her previous trips. She's only made one trip each to Egypt and France, and spent 6 days in each of them.
She already has the keystone, so I tried sending her there without going through the martial arts tournament and getting the amulet, but they key doesn't work. I'm sorely tempted to just open the door with debug enabler. I think I'm going to send her to Egypt instead. It's the only place she doesn't have a level 3 visa and a house. But first I'll have her get the adventure to get into the Terra Cotta Army tomb. It's the last tomb left, other than the Dragon Cave.
On her third trip to China, after she had gone to France and got the dragon cave key, when she arrived, the game asked which place to make her home there, instead of just taking her to her vacation house. After I selected her house, that's when I got the message that she couldn't complete the opportunity. So I had her do other things until her time was up, got the dragon cave adventure back with MC, sold her house in China, in case it was connected with the opportunity glitch, then go home and stay only until she could return. But she still got the message that she couldn't complete the opportunity.
So, I bought her the bigger house I wanted her to get, the West Royal House, and had her plant her garden and invite over the next two tournament opponents. She's now ranked at 4. I guess I'll have her finish the tournament too, before she goes home. She has the wish to win it, and I'd like to get that finished, so she has room for others connected with current places and events. It's worth 10,000 points, so I'm not going to cancel it, or her wish to master cooking.