Obsured chart data points
 

I appear to have conflicting requirements, but perhaps there's a workaround? I need to have labels on some data points (XY chart). Also, I need the user to be able to hover the mouse over a data point to see its value (standard Excel feature). My problem is that it appears the 'box' for the label obscures the data point. Is there a way to force one to the foreground and the other background/transparent?

I've also noticed that, if I select any single plot line on my chart, some of the data points are displayed in (black) boxes and others aren't. Why?