The problem is that the FE database is not linked to the BE database you updated.
When you open the FE, use the linked tables manager to see what BE the FE is linked to.
As the developer, you need a development environment. YOU cannot be modifying anything in a database that the user is actively using. YOU need a development copy of the FE AND a development copy of the BE. You make changes to your development copy of the FE. You compile and test and when the modification works, you "release" it to production. To do that, you replace the master copy of the FE that is on the server with the updated version. The next time each user opens his shortcut to the FE, it will open the updated version.
Changes to the schema are more delicate. Obviously you must make them in a test environment and then you have to somehow get the changes transferred to the production BE without altering the production data. I could write a book on this but it really depends on what you are changing. If you are adding a couple of new columns to tableB, I would probably make the change to the production BE ahead of time. always make BE changes during off hours or only after ensuring that NO one has the application open. After changing the production BE, I would copy it and make that my test BE. So, once I am ready to replace the production FE after I've changed the forms/queries/reports, they will find the new field already there. If your changes are more extensive that require deleting fields or changing relationships, you may need to develop scripts to implement the change to the BE to change the objects and also to change/move data. This is a case by case situation.
The last thing you do before releasing the updated FE is to relink the tables so your test copy now links to the production BE rather than the test BE. I never do this on my PC. I always move the production FE to the server and change THAT copy of the FE so I don't accidently leave my test FE connected to the production BE. Bad things can happen if you test a new delete query and delete production data.
Once you organize your working environment to minimize the potential for error, you are unlikely to make a mistake but I did one other thing that is intended to wake me up. I have code in the menu that looks at the BE's location. If the FE is running my my PC and the BE is the production BE, it puts a large red box around the menu to warn me. You NEVER want your test FE to be linked to the production BE.
