*tax code may only contain one assignment line*

Dear SAP gurus

I am getting error in posting in tax on sales and purchase

the error is

tax code may only contain one assignment line

messgae no FF731

Diagnosis

for direct posting to tax accounts, only containing exactly one tax lie item may be used.tax codes with several rates or non deductible portion are not allowed

procedure

use a diffrent tax code

for diect posting to tax account you ight have to define a separate tax code for which only one line with a percentage rate other than zero is active in percentage rate miantainnace all other lines must be active

plz help me out

thanks in advance