I have the same problem here. Actually everyone apparently have the same problem. Idk if its the feature of the game or just a mere bug, but its been like that from long time ago (at least thats how i've been through). You can watch ads 5x a day with the probability of getting 1-5seed or 10.000 coins. But opening the ads has its own probability itself.
So if u're patient enough and have some time to spare, u can try the ads link every 90s. if u're lucky the ads might pop up. and if u're lucky (again) u can get the 1-5seed or just 10.000 coins. i suggest u better not expect too much from it. Some player ever said that they can only get like 2 seed per week or so (just rumor tho) but it's add up.
Hope it's answer the question. Good luck seed (ads) hunting!