Subform data from date range

[Al]

I have a form which contains combo boxes for Vendor, StartDate, EndDate. In
a subform, I want it to display a graph made from the chart wizard which
shows data from another table (Profit etc...) along y axis and the date range
along the x axis where date range goes from StartDate to EndDate. So,
basically, the graph will show the profit made during each day (or week or
month) for a given vendor during a given time period...

My big question is how to make the graph in the subform display only the
date ranges from the selected combo boxes in the main form.

Any help appreciated!