appointments over midnight

Hello,
I am trying out different plugins to find something that fits a very specific booking process. Your plugin appears to be quite it – if you can help me with that problem:

When I set up the form i can choose how long a service should last – up to 24 hours (which is great). But unfortunately, when i do so it doesn’t work – there are no time slots available. Maybe the change from one day to another causes that problem? … or maybe it’s my fault and I did sth wrong ??

Thanks in advance, best regards,
Maya