The Yale data exposed the problem of being unable to calibrate/recalibrate sorted bam files unless read group information was explicitly added to them by bwa. The 0.5.8 (r1442) version of bwa does not support this capability. However, a patch for the same has been released at http://www.broadinstitute.org/gsa/wiki/index.php/File:BWA_read_group_patch.diff. The patch is for SVN version 45 of bwa. A patched version of bwa can be picked up from /ifs/scratch/c2b2/ip_lab/aps2157/ExomePipe/bwa/bwa-0.5.8c/bwa