Withholding tax calculation based on formula

Hi,

I am trying to apply some formula while calculating the withholding tax to a customer invoice.

I have used the formula range as:

10% upto 1000

20% for 1001-2000

30% for 2001 and above.

However the formula is calculating correctly for the range till 1000 but above 1000 the formula is not working properly. Kindly help me to resolve the problem.

I have configuration for your ref find the below attached file  , but at the invoice for e.g Invoice amt Rs 1500 . that time system deducted Rs .200 , why  this happening

WH Type

Thanks in advance