Hi all, I had already posted a message for the same problem but i think that my explanations were not enough clearly !!! I reformulate my question : what occurs when I try to create a library associated to a cdf containing probesets which are identical (the same probes have been designed for two different "targets" ... obviously these probes are not duplicated on the chip) ? Is it possible to generate expression values for all probesets from "affy" if there is probesets that are identical in the cdf file ? Best regards, Malick, AVIS : Ce courrier et ses pieces jointes sont destines a leur seul destinataire et peut contenir des informations confidentielles appartenant a bioMerieux. Si vous n'etes pas destinataire, vous etes informe que toute lecture, divulgation, ou reproduction de ce message et des pieces jointe est strictement interdite. Si vous avez recu ce message par erreur merci d'en prevenir l'expediteur et de le detruire, ainsi que ses pieces jointes. NOTICE: This message and attachments are intended only for the use of their addressee and may contain confidential information belonging to bioMerieux. If you are not the intended recipient, you are hereby notified that any reading, dissemination, distribution, or copying of this message, or any attachment, is strictly prohibited. If you have received this message in error, please notify the original sender immediately and delete this message, along with any attachments. [[alternative HTML version deleted]]