How to get Bn in y axis of a bar chart? Qlik sense

[manisha10]

Hi 

I have a measure where I am subtracting two values. 

=num(sum(Amount1)/1000000000, '##,### Bn)' - num(sum(Amount2)/1000, '##,### Bn)' 

The bar chart does not show Bn. It only show numbers on the y-axis. 

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