So the use of 'on' in the above sentence is incorrect. Actually I also know that 'on' refers to one date but I saw many examples where 'on' was used as follows:
...prizes, cameras and toys await the winners of the Boots Northern Ireland Children of the Year competition to be held on the 7-11th of September.Don't forget to visit the Yarn Fair for London, the South and South East at the Old Loom Mill, to be held on 17–20 September.These sentences are from the British National Corpus (some newspapers), which means they are supposed to be correct.On Jan. 25 a debate in the Assembly of Bosnia-Hercegovina ... endorsed a referendum on the republic's sovereignty to be held on Feb. 29-March 1.
Is 'on' here also used incorrectly? Or is there some difference between the way 'on' is used in these sentences and in mine?