In what scenarios can I use the RELATED function?

Alternatively, if I am unable to use the RELATED function while creating a column from another related table, what might be the reason?

The RELATED function can be used when there is an active relationship between two related tables. It allows you to retrieve data from the “one” side of a one-to-many relationship and bring it into the “many” side. This function is typically used when you need to reference values from a related table while creating a column.

If you are unable to use the RELATED function while creating a column from another related table, the reason could be that there is no active relationship between the tables, or the relationship is not set up properly in your data model.