If you’ve mastered your message, but don’t know how to properly promote it, then your problem is likely a marketing one.
Maybe you’re not skilled at writing copy or designing graphics that capture attention and call to action… or maybe you have the right-brained stuff down, but struggle with the more left-brained things like collecting and analysing data, and using those insights to inform your strategies and tactics.
Or maybe it doesn’t look like that at all - maybe you know what you’re doing, but don’t have the time or energy to implement. Perhaps you’re just spread too thin across tasks, that you’d rather delegate these duties to an agency who can take care of everything for you. This counts as a marketing problem as well.