Hi M.,
At nine months, you are probably only producing exactly what your baby requires, so there's not usually a lot of excess to actually pump (esp if it is right after a feeding).
To road test, try skipping a nursing session and give the kiddo a bottle of formula (don't worry, she'll live!) then pump what she would have ate. You should test this when you are pretty full, so you KNOW milk is going to come out (the fuller you are, the easier the letdown).
If you STILL aren't getting any milk, THEN it might be the pump.
CHECK THE VALVE MEMBRANE FIRST--it's the easiest thing to over look. While the pump is on, you should see the membrane pulsing in and out (I'm assuming this is electric/battery operated?)if it's not, it could have a hole/tear/crack and need to be replaced. If its not that, check for other gaps, holes, leaks along the rest of the tubing and connectors.
Check babys r us for replacement parts (they have quite a few for some of the pumps) or got to the manufacturers website.
As for increasing supply--nutrition, hydration, stimulation.
...And you can be creative on the stimulation ;)