There's no guarantee. Reality checks confirm lucidity, but they aren't great at inducing it. Honestly, it's a flawed method that works better for some than others. Why? It has too many opportunities to fail. First, you have to notice a dream sign. Then you have to perform an RC. Finally, it has to be successful--since you're not lucid until that final step, sometimes your mind will rationalize anomalies. And there's no guarantee any of these chances will appear in your dream. Not trying to make it sound hopeless, only saying that your frustration isn't unwarranted, and not entirely your fault.

All reality checks do (while we're awake) is to form a habit that will hopefully transfer into our dreams and make us a lucid. But that's only part of the equation. I'd explore other methods alongside this one to see which you have the most success in. Personally, I go with the wake back to bed methods.