Table View Cells Show Black When Expanding

I have a table view set up and when a user selects one of the rows, it expands downward and shows a sub-list of cells (that are inside the selected category). When the cells expand downward though, there's an ugly black animation at the bottom of the cell. Also, if I drag the table view down, as if I'm scrolling to the top of the page, the very top (empty area behind the table view) shows black as well. I have everything I can find set to white... so I don't understand why there's black. A little help would be great. Thanks!