supervised classification by envi+dil

pro example_class_doit
     compile_opt idl2
     envi, /restore_base_save_files
     envi_batch_init, log_file='c:\batch.txt'
     envi_open_file, 'C:\can319398.tif', r_fid=fid
     if (fid eq -1) then begin
         envi_batch_exit
         return
     endif
     envi_file_query,fid, ns=ns, nl=nl, nb=nb
     dims = [-1l, 0, ns-1, 0, nl-1]
      pos =lindgen(nb)
      out_name = 'C:\22.img'
 
ENVI_DOIT,'CLASS_DOIT',dims=dims,FID=fid,METHOD=4,pos=pos,OUT_NAME=out_name,CHANGE_THRESH=5.00,ISO_MERGE_DIST=2,$
ISO_MERGE_PAIRS=2,ISO_MIN_PIXELS=1.00,ISO_SPLIT_SMULT=1,ITERATIONS=5,MIN_CLASSES=5,MUM_CLASSES=10

envi_batch_exit
end
why the process result is a '*.sat' file,  where error?
thanks