Is it possible that you have a typing error? See below in RED:

=IF(COUNTIF($X$10:$X$270,X268)>4,AVERAGE(SMALL(IF($X$10:$X$270=X268,$AM$10:$AM$270),$AS$5)*$AS$6,SMA LL(IF($X$10:$X$270=X268,$AM$10:$AM$270),$AT$5)*$AT$6,SMALL(IF($X$10:$X$270=X268,$AM$10:$AM$270),$AU$ 5)*$AU$6,SMALL(IF($X$10:$X$270=X268,$AM$10:$AM$270),$AV$5)*$AV$6)*4,AVERAGE(IF($X$10:$X$270=X268,$AM $10:$AM$270)))