charting a calculation...

i have a business solution that I created 6-7 years ago and it's multi-user db running on amp server on a dedicated mac mini.

it's been running my business for years. I've recently added a dashboard tab so that I could view key metrics on my business.

I run a business where customers send me their circuit cards for repair. I repair them and send them back.

I'm trying to create a simple bar chart that shows how many cards (or records) that I have in backlog which gives me an idea of how much business I have "in-process".

I can accomplish this by counting the number of records where the airway bill tracking number field is empty because when this field is empty, I haven't finished repairing the card and have not shipped it back to the customer!

This sounds simple but I do not know how to accomplish this task. Can somebody give me an idea of what the function is to do this and what values to use in the script function?

I would really appreciate it. Randy