Dear BioC people Could it be that neither detection.p.value (simpleaffy) nor mas5calls (affy) work with Hu6800 chips? I get the following errors: > M17 <- ReadAffy(filenames=c("M17.cel")) > dpv17 <- detection.p.val(M17) Error in if (alpha1 < 0) { : missing value where TRUE/FALSE needed > dpv17 <- mas5calls(M17) Getting probe level data... Computing p-values Making P/M/A Calls Error in if (y < alpha1) { : missing value where TRUE/FALSE needed > dpv17 <- mas5calls(M17,ignore.saturated=F) Getting probe level data... Computing p-values Making P/M/A Calls Error in if (y < alpha1) { : missing value where TRUE/FALSE needed > Best regards Christian Stratowa