How to format a cell as Currency?

I am attempting to format a cell as currency with AUD as the symbol

I have attempted to use a custom style of "[AUD]#,##0.00;-[AUD]#,##0.00’’ (and various other combinations) but Excel complains with a "file Error, some file formats will be lost"

Any idea how I can format a cell so that currency appears something like -AUD123.99?

Thanks in advance

Could you please post your sample code here? A sample project is more helpful to figure out this problem.

And you can try this attached version.

Have worked out how to do this. The currency must be formatted like [$AUD], i.e. the currency specifier format is [$]