I'm trying to create a Crystal Reports formula field (to calculate the percentage change in a price) that will return "N/A" if a particular report field is null, but return a number to two decimal places using accounting format (negative numbers surrounded by parentheses) if it is not.

The closest I have been able to manage is this:

If IsNull({ValuationReport.YestPrice}) Then
    'N/A'
Else
    ToText({@Price}/{ValuationReport.YestPrice}*100-100, '###.00', 2)

However this represents negative numbers using a negative sign, not parentheses.

I tried format strings like '###.00;(###.00)' and '(###.00)' but these were rejected as invalid. How can I achieve my goal?

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