Background color of checkboxes in datagrid

hi My problem is the following: I've a datagrid with a column with checbox, and when I check or uncheck a checkbox the background color of the cell switches to black, instead of the color used to mark a row as selected. All the examples of how to use the datagrid shows the same behaviour (black background for checkboxes and another color for other columnstyles) Is there some way to prevent this? /Stefan