Hi I am using ENVI 5.0 SP3. The data I was processing is from HJ-1A satellite, which was launched by China. When I tried to make atmospheric correction using FLAASH, it did not work. The following is the error message. Problem: The FLAASH program exited with the following errors: ACC error: avrd IDL error: POINT_LUN: Negative position argument not allowed. Position: -1994441936. Unit: 102, File: E:\HJData\HJ1A-CCD1-450-64_BIL. ACC_AVRD ACC_HYPER2 ACC_ACC ENVI_ACC_EVENT ENVI_FLAASH_PROCESS_MANAGER IDLRTMAIN $MAIN$ Any help would be really appreciated! Thanks.Long MA