Num error in formula

Hello Experts,

i have a monthly data in sheet one, i am trying to sort by the largest amounts in sheet 2 with a formula, i get a num error with the formula i used, i so realised that when two figures have same figure it repeats the first instance all though i thought the below formula will resolve that. kindly assist to sort the data by the largest amount and deal with the num error. thanks



INDEX(Sheet1!A$2:A$21,SMALL(IF(Sheet1!$N$2:$N$21=P20,ROW(Sheet1!$A$2:$A$21)-ROW(Sheet1!$A$2)+1,""),COUNTIF(Sheet1!$N$2:N19,Sheet1!N19)))

Thanks special K, This problem with this solution is it repeats an item i want to return if the figures are the same, i want to prevent that from happening, could you adjust the formula for me. Pls not a VBA solution