updated sixhours theme but child theme not working

I have updated Sixhours but can’t use the child theme that I was using as the update is so different. I have made a new child theme, but it just doesn’t work. Below is my style.css, is it wrong?

/*
Theme Name: My Theme
Description: Child theme for the sixhours theme
Author: My Name
Template: sixhours
*/

@import url("../sixhours/style.css");

#site-title a {
    color: #009900;
}

Should the Template name above be sixhours or Sixhours? I’ve tried both but it just doesn’t work.