Probably visual bug. Please fill this report form for me and add dates when you tried Luck spin so we can check how much coupons you actually received.

Platform (Browser/Facebook/Client) :
Server ID :
Character Name :
UID (If you are using Facebook account, you can find your UID on the bottom of the page. For players with OAS account : go to your profile - "change nickname") :
Bug Description :
Screenshot :
Operation System :
Resolution :
Your computer time-zone/Country :
Are you using VPN or not ? :