Can a walkin be larger than the zone containing it?

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Having some trouble with modelling walkins for a supermarket. My walkin is served by 2 evaporators, running on 2 separate transcritical systems. I'm modelling this by effectively splitting each walkin into two halves and assigning half of the total heat-loss surface area to each evaporator, along with "half" a door. I have a zone specifically for this walkin to occupy. My objects look like this:

Although I have specified the zone that they occupy and the "total insulated surface area facing zone", I am getting an error to say these values are missing. Is this because the geometry doesn't add up, for example the floor area of the walkin may be larger than the floor area of the zone? Or is it having 2 walkins in one zone? Or something else? I can't find anything about walkin geometry in the Eng Guide/InputOutput. The fatal error I'm getting is:

* Severe * <root>[Refrigeration:WalkIn][ATH074_FreezerStore_201][zone_data][1] - Missing required property 'total_insulated_surface_area_facing_zone'. * Severe * <root>[Refrigeration:WalkIn][ATH074_FreezerStore_201][zone_data][1] - Missing required property 'zone_name'. * Severe * <root>[Refrigeration:WalkIn][ATH074_FreezerStore_201][zone_data][2] - Missing required property 'total_insulated_surface_area_facing_zone'.