Tree preservation zone

There is a problem

1000 entries with tree-preservation-order field must match the reference field in the tree preservation order dataset

reference: TPO57
name: 1/1973
tree-preservation-order: undefined
1/1973
tree-preservation-zone-type: area
geometry: MULTIPOLYGON (((0.584750 51.290016,0.584895 51.289708,0.585027 51.289489,0.585118 51.289371,0.585160 51.289289,0.585152 51.289165,0.584958 51.288844,0.583743 51.287496,0.583212 51.286925,0.582938 51.286557,0.583489 51.286480,0.583903 51.286407,0.584504 51.286260,0.584899 51.286223,0.585253 51.286216,0.585542 51.286224,0.587152 51.288404,0.587170 51.288446,0.587168 51.288507,0.586782 51.288665,0.586242 51.288936,0.586069 51.289002,0.585382 51.289305,0.585609 51.289552,0.584907 51.289989,0.586423 51.291825,0.586343 51.291822,0.586268 51.291835,0.586248 51.291864,0.585944 51.291504,0.584750 51.290016)))
point: POINT (0.585199 51.287846)
notes: County of Kent (Hollingbourne Rural District) Tree Preservation Order No 1 of 1973, under Section 60 of the Town and Country Planning Act 1971. Area of Trees - A1 the several trees of various
organisation
entry-date: 1973-01-04
start-date: 1973-01-04
end-date

Your dataset is missing the tree-preservation-order column.

The Tree preservation zone guidance explains how to fix the issue:

The reference for the tree preservation order that covers this zone.