I agree with the other folks here that something's likely wrong with your offer and you need to dig to figure out what that is.

BUT, I also sell online courses, and you should know that conversion rates here, like for everything we all sell, are low. You have to get a high number of people to a landing page to convert enough of them to make it worth your time. Even if you have a relatively high conversion rate, you need a lot of eyeballs to make it work. So just keep that in mind!