Hi Sarah,
Have you tried changing the item type to either 'Wind speed' or 'Wind velocity'? When selecting the input file, you can check the possible item types in the tab 'Constraints info'.
Note that you can also check out the example installed in the folder C:\Program Files (x86)\DHI\2014\MIKE Zero\Examples\MIKE_21\SW\NorthSea
Best regards,
Mathieu