Hi, I am trying to use the gene logic dilution series of data to compare a few different methods of calculating expression signals. However, when I use any of the data from that set (cel files of the hgua95 set) all the values for a given probe are identical if I use the rma methods through expresso. If I use the rma function or try to calculate mas values I just get files full of NA. As far as I can tell this seems to be restricted to cel files for the hgu95a set as I have no trouble putting our data through bioconductor (MGU75v2 series of chips). Neither does there seem to be a problem with the data itself as I can easily put this through dchip or several of my own programs. The R environment doesn't spit out any error messages at all during this processing, so it is a little difficult to work out what might be going wrong. Has anyone else out there come across something at all similar, or does any one have some ideas as to what might be causing this problem? I am grateful for any suggestions, cheers, Martin -- Martin Jakt Stem Cell Biology Group Riken Center for Developmental Biology Kobe Japan