You need to set the ItemWidth property to match the rotator's Width property. If you want the Up direction to work you have to add it to the ScrollDirection property. As a final note - the items cannot fill the viewport of the rotator - they are four, 30px tall each, summing up to 120px, but the rotator is 190px tall. There is no way for this to "rotate", so you should consider reconfiguring the sizes or adding more items. For example:
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