Hi Thomas:
Here is an example - it requires re-arranging your data a little bit.
menu: Graph, Chart (the key is two categories, here: (date and field)),
If you do it interactively, first result is a paired-bar graph - transformed via the
Stack Bars option under the red-triangle.
e.g.
date field Amt
01/05/2011 A 211
01/05/2011 B 213
02/05/2011 A 500
02/05/2011 B 633