Captcha Not Working, Image is not visible

I just purchased the eshop. I am trying to enable the captcha during checkout and it is not working. The captcha image is not appearing. What steps can I take to get that working?
Thanks!

Hello Terrihatton,

Thank you for purchasing our EShop Shopping Cart extension. EShop is using ReCaptcha of Joomla. Please make sure that you enable ReCaptcha plugin in Joomla and choose ReCaptcha as default capcha of your site under Configuration of Joomla.

Hope that this will help.
Sincerely, Giang