1) Copy following link to identify Leviton 6200 series 12 hour countdown timer and download manual:
http://waterheatertimer.org/Countdown-timer-horsepower-ratings.html#6230

2) I think you have timer wired wrong:
Copy following link and read ez steps how to wire single-pole timer:
http://waterheatertimer.org/How-to-wire-timers.html

3) Add comment and describe what type switch you are replacing.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7