Answer posted by Dan Letecky [DayPilot] 10 years ago.
It might be a CSS issue. You can check whether the CSS is being applied properly using Chrome developer tools - the row header columns should have *_rowheader_selected applied (where * is the theme name).
If the selected rows are marked with the CSS class properly you will need to update your theme - create a new one using the theme designer at http://themes.daypilot.org/.
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