Probably, you are trying to add this code directly to an email created in your email client (for example, Gmail, Hotmail or Outlook). The countdown timer will be displayed correctly if the letter is formatted as an HTML document, and not as plain text. Most email clients support HTML, but not all of them provide a simple way to create HTML emails. We recommend to use html email template, for example, MailChimp, Campaign Monitor, ActiveCampaign.