Slitherine

Hello,

I was thrilled to find an anniversary coupon from Slitherine in my inbox today. My question is, can I use it on an already discounted title or do I need to wait for the current discount to expire? I'm getting an error message (coupon not found) which is why I'm asking.

Thank you.

EDIT: Never mind, I was typing the code incorrectly, the percentage number was actually part of the code. Ops!