I posted an ad for jobs available at my company and received only 1 CV in response.

The problem was, people - in my opinion - especially some job seekers, abuse the service by frequently re-posting their ads. Some of them re-post several times per hour.

This automatically pushes your ad many pages back very quickly, which reduces the chances of anyone actually seeing it. My ad was on the 10th page within 2 hours.

Therefore, I believe the newspaper is a more sound option.