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: ZZZZZWESRW950
name: Eton Rural District Tree Preservation Order No.6; 1973; dated 26/3/73; made under Ss.60 & 61 of the
tree-preservation-order: undefined
TPO/ER/1973/06
tree-preservation-zone-type
geometry: MULTIPOLYGON (((-0.563535 51.589426,-0.564398 51.589359,-0.564388 51.589283,-0.564379 51.589250,-0.564380 51.589248,-0.564374 51.589231,-0.564346 51.589049,-0.564327 51.588961,-0.564326 51.588950,-0.564295 51.588830,-0.564282 51.588769,-0.564271 51.588691,-0.564271 51.588678,-0.564261 51.588630,-0.564251 51.588618,-0.564240 51.588610,-0.564228 51.588604,-0.564197 51.588595,-0.564171 51.588592,-0.564139 51.588592,-0.564099 51.588593,-0.563958 51.588604,-0.563844 51.588617,-0.563808 51.588623,-0.563708 51.588647,-0.563613 51.588676,-0.563542 51.588701,-0.563515 51.588712,-0.563419 51.588759,-0.563434 51.588830,-0.563474 51.589051,-0.563535 51.589426)))
point: POINT (-0.563908 51.589016)
notes
entry-date: 2017-07-04
start-date: 2017-07-04
end-date

Your data is missing a tree-preservation-order.

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

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