Hi, We have a batch of arrays that have some problems with one of the printtip, which resulted in a lot of missing values just for that printtip (eg. 285 missing values out of all 300 spots). Of course it generates error when normalizing with maNormMain(., f.loc=list(maNorm2D())). Now we still want to do printtip loess normalization, is there a way to ignore just that printtip? Thanks a lot! Bin