qgis - Table Join Resulting in NULL

I'm trying to join a field named "Area" belonging to the shapefile 'Ancient Woodland' with the shapefile 'Net Development Area' (see screenshots below). The results only return 'NULL' which I don't understand because the field type of "Area" is a number. Even if I join the entire table to Development area all the entries return 'NULL'

Both shapefiles have a common field which I'm using to perform the join ("Substations"). Surely I don't need to create a .csvt to do this?

Answer

Table join doesn't work that way, you need to select two columns that contain the same text for features that you want to join.

So in your case you need to choose Substations in both Join and Target field.