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This seems working fine for me when I tested the widget. Did you try it when you preview your form?
I checked the date reservation in your cost generator form and it's limit is currently set to 1.
Please make sure to set it to zero and then save your form.
Let us know if you continue to encounter this problem.
By the way, I just want to emphasize the "days limit". It is actually the number of dates you can pick in the date reservation widget (calendar).
Example, if you put 3 on days limit, you can only select up to 3 days in the calendar.