You cannot send messages because you have reached the limit of the allowed messages you can send within 24 hours, 7 days, or 1 month.
This is part of Sitly's fair use policy: it is intended to prevent spam and allows the recipients of your messages to have sufficient time to respond. It is a way of guaranteeing the quality of our childcare platform. Sitly Premium users can send many messages before the daily, weekly, or monthly limit is reached. We recommend that you give the receivers of your messages some time to respond before you contact new people. And, of course, you can check back later, to start new conversations again.
In our Terms of Service, you’ll find article 5.4.e, which explains that once the message limit of the site's average is reached, users begin to perceive messages as spam.
This only applies to messages to new users or users that you have not contacted before. You can always continue to respond without a limit to users that you have already contacted.