Error calculating in jasper report-Collection of common programming errors

I have two fields as a total of a group and I’m trying to calculate the variance in a third field. this is how I’m trying to do:

 // Checking divisor is zero
 ($V{BigDecimal.toString()} == "0") ?  new BigDecimal(0) :
(new BigDecimal(
$V{BidDecimal1}.toString())
     .subtract (new BigDecimal($V{BigDecimal}.toString()))
     .divide(new BigDecimal($V{BigDecimal}.toString()), MathContext.DECIMAL128)
     .multiply( new BigDecimal(100)
)

However, I’m getting a Division undefined error. Sometimes I got a Division by zero error too.

Thank you for any help.