Resident evil the darkside chronicles?

so iv'e been playing the game for a few days now. The chronicles mode. Like story mode. I recently got to the level/chapter with the alligator boss. I beat it. After you beat a level or chapter you go to the main screen and press chronicles again to go to the next level. But this time it did somethin different, it showed me two pictures of the 1st two levels and it was called senerios. I did one of them its just repeating the same level. im confused. Why wasnt the level the one after the alligator? help?