You have no code there to display anything.

If resultLabel is actually a label and you want to display something in it then first you need to drop the definitions from your routine as you are overriding it and defining it as a Decimal.

To assign the value to the label you would use something like
Code:
        resultLabel.Text = (num1Decimal + (num1Decimal * resultADecimal) + (num2Decimal * resultBDecimal) + (num1Decimal * resultCDecimal) + (num1Decimal * resultDDecimal) + (num1Decimal * resultEDecimal)).tostring