Hi all trying to read U133A chips, gave me today (under R 1.8.1 + XP Pro) with affy 1.4.4 : > library(affy) Error in if (a[k] > b[k]) return(1) else if (a[k] < b[k]) return(-1) : missing value where TRUE/FALSE needed In addition: Warning messages: 1: NAs introduced by coercion 2: NAs introduced by coercion Error in library(affy) : .First.lib failed anything to do with the new affy format ? thanks Phil [[alternative HTML version deleted]]