To reproduce: - Add RadCalendar to a blank form and set its AllowMultipleSelect property to true. - Select a date and deselect it right after that. You will notice that the background is not changed. - The cell is actually deselected but it appears as selected since it is the focused cell and the styles are equal. Workaround: Change the style for the focused state, which will allow the user to distinguish between focused and selected cells.