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I have just bought a used Casio 1600 and found that the sustain pedal (not a Casio one) works in reverse - pedal up to get sustain and pedal down to stop it.
Could reversing the wires in the audio jack, center to shield and shield to cemter make it work correctly?
Grateful for any advice.
(Also posted in Casio Keyboards)

Nope...
Two choices:
1) return the pedal from where you purchased it to get the right one for your Casio, or your money back.
2) Open the pedal, and see if there is a third contact on the actual switch. It will just be a case of reversing the polarity of switch.

Some keyboards will have a option to reverse the sustain pedal polarity, I would guess the Casio hasn't.
You can purchase pedals with polarity switches, again I assume this one hasn't.

I tkink Roland use a pedal down = contact closed type action.
Yamaha (& Casio I think) use pedal down = break contact action.

Is there a polarity switch on the pedal, or polarity setting on the kb?

I found out that my 'sustain' pedal was in fact a volume pedal! I took the word of the seller what it was, So problem deleted.
Thanks to all who responded.