Forward date arrows is not working

The forward or next button on dhtmlxScheduler is not working. It works on three of the tabs except for the first one( which is Persons tab in your example http://dhtmlx.com/docs/products/dhtmlxScheduler/sample_units.html)

Please help on this.

Hello,

Checked the sample you linked and back/forward buttons seem to work correctly (they switch days in Persons view).
What browser do you use and is there any javascript errors?

Best regards,
Ilya