Hi Gabriella, Is RECID declared to be an integer? Has NCID been changed after the netcdf open or create, so that it no longer refers to the netCDF file you think it does? Either of these problems might cause the symptom you are seeing. Otherwise, what happens when you run "ncdump -h" on the netCDF file? That will call the C inquire function to find the ID of the unlimited dimension and could tell you if the file is corrupted. --Russ Russ Rew UCAR Unidata Program address@hidden http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: AEY-440212 Department: Support netCDF Priority: Normal Status: Closed