AdSense rejected without the most common message like "Low value content."

Hello, Wondering if anyone has an idea what happened with my AdSense application. Submitted application 4 days ago, and get the following message today: # "Your account has not been approved. You need to correct some issues before you can use AdSense". No other words, even the most common message like "Low value content." Highly appreciate if anyone could explain this situation. THANK YOU.