Postcode and State fields are populated automatically. If you start typing your suburb in the suburb box the post code and state should populate for you. Sometimes there can be a slight delay depending on the speed of your internet connection, so please type your suburb slowly or type your suburb and then click the TAB button on your keyboard.
Do not type your suburb, state and postcode all together on the one line in the suburb box, as this will result in an error
Please try this and advise if you still have any problems.