Changing 'KPI Visualisation value' from blank to N/A

Hi All,

I am currently using the KPI visualisation to show the KPI Metrics.

By default, Power BI show (Blank)! in the measure if there is no data.

However, I want to change it to "N/A" instead. Does anyone know how I can achieve this? 

I have tried using a DAX queries, if a+b=blank(),"N/A",a=b.

However, is still showing (Blank)!

Any helps is appreciated!

Cheers,

Kev