crazy_dave: Do you mean that the worker never arrives at the far granary? - despite it being the only granary accepting supply?

Have you made sure that the roads are truly connected? (sometimes the view can hide the fact that say a corner in the road is not actually connected)

For trade and export one usually uses warehouses rather than granaries and the traders come to the warehouse to pick up their supplies.

KrankyKat: Long distance granaries are a pain but can be done. But you basically have to build a ton more granaries (and farms) than you would normally, in a chain down the line. Having a couple granaries near the area that needs the food is not sufficient.

You build a lot of granaries closer to the actual farms (build more farms than normal), so they fill up quickly. Then the granaries at the far end that need the food will go to those middling granaries to grab the food. Chain.

If this is the map I'm thinking of, I would not sell wheat/food as an export in this situation. Use the other options, like weapons, IIRC.

If you must have people closer to the entrance areas for early trade building worker access, leave them as tents for as long as possible - no food required - and plan/build the main population area closer to the farmland. Don't forget that once your main town is established, you can always get rid of the starter hovels and move the trade closer to the main town.