1. If you have problems with Airdrop setup, make sure your Mac can actually use Airdrop by checking to see if 'Airdrop’ is listed under the Finder’s Go menu. I take it your iPad/iOS is new enough to be Airdrop capable.
2. Check out
Use AirDrop to send content from your Mac for the proper procedure to follow.
3. If (2) went initially OK, but now it doesn’t work anymore, check out
Apple Pay, AirDrop, and Han...k again.