After you done certain quest at bunker hill you can build a trading post at any settlement, my question is...why don't the traders use it when they come to the settlement? Like Trashcan Carla, when she comes to Sanctuary Hills she Always block the road outside the house where the first settlers from Concord go to...why doesn't she go to the trading post you have built???

She does for me if someone else isn't already using it like the doc or the armor guy.

that is a good question.. She could potentially be a great resource of caps for you restocking herself!

Well no one at all is using it, and i don't get any other traders coming to sancturay then trashcan carla?

Sanctuary is probably on her route, but not the others'. If you set up a Settlement IN Bunker Hill, I would think more traders would swing through there (but I don't know of any other than Carla).

I set up those trade stations at every settlement, and more or less every* merchant eventually shows up. I've even had two merchants visiting Sanctuary simultaneously (maybe three - maybe - take it with a grain of salt).

*That said, I've also had times when no merchant is visiting a given spot. And also, I've seldom seen a merchant visit Coastal Cottage, though I wonder if I need to place it in a more hospitable location (not on the uphill slope from the road).

Well have to wait and see what happens, but it think this is bugged like a lot of things still is in FO4

I have one set up at Sanctuary, and I get all of the caravan traders there. Cricket, Doc Anderson, Lucas Miller, and Trashcan Carla. They all use it, but only one of them will use it at a time. Carla seems to still prefer her default spot in the road sometimes though. That could be due to her showing up when another trader is already there and using the caravan post though.

Mine at Sanctuary work for me. All the vendors show up and are at the assigned space. If you place it in a weird place that doesn't give them enough room, they might go to their default space like with Carla.

Scrapped one of the ruined houses in Sanctuary and made the foundation a central place where the travelling traders congregate. Unknown about Bunker Hill. Build area is to constrained to craft travelling trader stands.

I scrapped a whole house with Foundation and placed Everything easily for them to reach / go to, but still no other traders then Carla and she Always uses here old spot

Bunker Hill shouldn't need it - Stockton's merchants rotate through one of the shop areas near the back of the main building.