Sounds you created the relationship in the wrong direction.
Starting on the primary entity, a 1:N allows a sub-grid but a N:1 gives you a look up field (this entity is no longer the primary, but rather the child type).
Sounds you created the relationship in the wrong direction.
Starting on the primary entity, a 1:N allows a sub-grid but a N:1 gives you a look up field (this entity is no longer the primary, but rather the child type).