AS385BN-2.5 voltage reference - how to use?

I bought some AS385BN-2.5 voltage references and I'm not sure how to use them. One of the diagrams in the datasheet shows what I'm shooting for (the diagram is from another company's sheet because Alpha's is unreadable - same diagram - different part number)

I'm using 5V instead of the 9V in the diagram. Max forward current is 10mA.

I've tried various resistors, but I get every voltage but 2.5V out of the thing. How do I determine the resistor value?

Here's the datasheet: View attachment AS385BN.pdf

Looks like a regular shunt regulator. I use the TL431 and it works like a charm, connects much the same way but needs a smaller resistor.

A bit more fooling around and I got it working. I had it connected backwards. Funny how they won't work right when you do that.

Shunt regulator == glorified zener diode?