The cache is not located at the given coordinates.
Once you've completed the Adventure Lab "Supply and Demand" you'll recieve the coordinates to allow you to find this cache. Of course it shouldn't surprise you to know that the location you're heading to was also once a brick pit.
I hope you've had fun wandering around the Marrickville area and can imagine the role these places played in history of the area and the changing nature of how we live and work.