I get a pie chart displayed when I use the line example from Instructions. The same is displayed when line is changed to pie. Weird. Also the labels aren't displayed and according to code it looks like they should be. I'm using the current MSIE and Chrome with WP 3.8.
Otherwise it's a nice plugin.
[wp_charts title="linechart" type="line" align="alignright" margin="5px 20px" datasets="40,43,61,50 next 33,15,40,22" labels="one,two,three,four"]