Are your buildings funtioning is the first question.
If they aren't you will see a sack with a sign through it saying its stopped production. Not knowing which buildings you are referring to I can't say exactly what the problem is since all industry would have different issues.
BUT you said farms, so I am assuming you are trying to export farm material.
Papaya, Pinapple, Sugar, Tobacco and Coffee and banana be exported I believe, So I would guess you need to check to see if your population is consuming the food you are trying to export.
A good idea is too always build at least two fishing wharfs near the start. This gives you a pretty decent excess food at the beginning and it opens up farms for cash crops.
Make sure they are near roads, have a garage near the dock so your teamsters can travel more quickly, and one near your farms. Also make sure you have a full compliment of teamsters.
Make sure your farms are fully staffed and have good wages. Now if you are trying to can them,. roll them or destill them thats another issue.
And don't forget farms take several months to turn a profit, they don't instantly turn over like oil or mining. It can take up to a year or more before you start exporting goods.
The last thing I can think of is you are putting farms down on the wrong soil. If you don't know, certain crops can only grow in certain locations, so putting a coffee farm on a location where only sugar grows means generally little to almost nothing will grow, giving you zero exports.
the green areas when you select the farms are the only places you should be placing them. So if you select a farm and click coffee you will have to look around to find soil that in can grow in then place it there.
The other trick with teamsters is having a clean run between them, the production building and the docks. If they have to travel through your main town just to get to the docks you are going to hit big problems later on when the amount of traffic slows the transport of goods to a crawl. It can help to build a second dock which is more easily reached.
When it comes to farms, obviously you need to check the usage of items. If you are producing only just enough food to feed the population then don't expect any exports.
I'd suggest eyeballing the problem manually. Click on a farm and see what it says about output storage and recent production. If they have a large number in output storage it means the teamsters can't reach your farm to gather the goods for some reason. Alternately, check that your teamster buildings actually have workers. If there is no output storage and no signs of production then check that the soil is suitable for the crops they are trying to build and that there is enough room to actually grow crops.