Can't get calendar to highlight available dates

I can't seem to get my calendar to show dates that are available. I'm including a screen shot. As it is, my clients have to choose a date in hit/miss fashion to see if there are any available time slots. Changing color settings in layout has not helped. Can you help?

Sorry. What product you are using, is it Events Booking or OS Services Booking?

This layout looks different to me, so maybe it is a different product?

Please let me know so that I can answer your questions further

Regards,

Tuan

It's OS Services Booking.

Hi Julie,
The Top-left calendar will only show the different colors with
- Passed dates
- Off dates
- No Services available
- No Employees available
- Venue isn't allow to book
The Calendar won't able to show different color with the dates that having no available timeslots.
Thanks
Dam