Sorry just saw this!! But hmmm I’m not really sure!! I did Google and it says it can take 48 hours for it to start killing new ticks so that would still be about the time frame I suppose so I would think it’s just that. Although sometimes it doesn’t always work but I think in your case it’s because it’s so new.@TheDawg, I had got that Seresto collar for my dog. I don't know if it's helping any with the ticks. Yesterday I pulled two attached ticks (one on his chest, other on his belly) off of him and today I saw a tick climbing up his fur to get to him near his collar! The collar finally came in the mail Monday, and I put it on that day. Is it not appearing to work because it is new, or is there something else wrong?