The current version of RadTimeBar for Silverlight does not offer a way to specify the current group
or item interval. The control itself picks up the best possible intervals to show out of its Intervals collection. The best possible intervals are actually, the smallest possible intervals so that the timeBar shows as much information as possible.
I suppose, your zoom level does not allow the timeBar to show the Day interval and in case you change it, you might be able to make the timeBar show the Day interval. For example, you can make the VisibelPeriod a week.
Please note, that due to a limitation in Silverlight framework, we have enforced a constraint for zoom-in to maximum of 30 000 pixels. That is why, depending on the period range that the timebar shows, the minimum interval that can be displayed, might be different from the minimum interval that you have added in the Intervals collection (the day interval in your case).
the Telerik team
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