Soon after, the duo released their debut album "Day by Day" on December 9, 1999, and made their first official television appearance two days later. Unlike their predecessors on their label, popular teen idols at that time, they shied away from upbeat techno and dance music, opting for mid-tempo ballads. The debut became highly successful selling over 250,000 copies. The duo acquired status as the next-generation stars as they won Best New Artist award in 2000. At the same time, the duo failed to rise to instant stardom unlike their predecessors such as H.O.T., whose album sales have passed the one million mark.