Hello Felicity-crabtre

We have had a look at the screen shot and we can see all mandatory boxes have been selected so all looks good on that side. It looks likely it is the CSV itself. Did you format the cells for date on the CSV? It could be it can not read that column or that other columns not needed have something causing the block.

Can we ask you to in the excel remove any columns you do not need and once done  right click on the top of the column for the date >go to format cells>date>ok>save the file as a CSV and then try and upload again.

Let us know if that works for you