Dongjoon, Kevin, and Hyungshik from ZE:A have revealed 'I Don't Know Why', featuring V.O.S's Choi Hyunjoon. A representative from Star Empire expressed, "'I Don't Know Why' was composed by Choi Hyunjoon, and sung by ZE:A's Dongjoon, Kevin, and Hyungshik. This song is part of 'Chosun Police 3' OST and was released through Bugs Music on the 7th. Even though V.O.S is preparing for a special mini-album to be released on the 17th, Choi Hyunjoon still made time to create this song for 'Chosun Police 3'. This song will challenge the members of ZE:A as it's their first time singing a ballad.' 'I Didn't Know Why...' has mournful lyrics and a touching melody, which will further highlight the adventure, mystery, and sadness of 'Chosun Police 3'. Check out the track below: http://www.youtube.com/watch?v=Z95UpnUG56M Thanks to everyone who sent this in.