The Hague Convention on the Civil Aspects of International Child Abduction applies only to cases and situations of child custody wrongful removal or wrongful retention that occurred after it was put into force between two countries. Not all countries agreed to this Hague Convention on the Civil Aspects of International Child Abduction at the same time, and some countries are still in the process. You can check on the status of a country here.

Article 35

This Convention shall apply as between Contracting States only to wrongful removals or retentions occurring after its entry into force in those States.

Where a declaration has been made under Article 39 or 40, the reference in the preceding paragraph to a Contracting State shall be taken to refer to the territorial unit or units in relation to which this Convention applies