I encounter an error when I run my batch mosaic pro in IDL. I calculate all the parameteres that the mosaic_doit require. There is no problem before it run to ENVI_DOIT, 'MOSAIC_DOIT'. After runs to 'mosaic_doit' and the 'Data Mosaicking' dialog displays on the screen, which says 'Number of input files:2. Output File: ~path+.img', it comes across the error: ENVI Error. mosaic_doit: An error has occerred during processing. Error:"Variable is undefined: STV." The result may be invalid. Then it stops. I have not applied STV in my program and I cannot look up something about STV in the whole pro. I run it in Classic+IDL and ENVI5.1+IDL environments and both encounter the error. input related to mosaic_doit is as follows: envi_doit, 'mosaic_doit', fid=in_fid, pos=pos, $ dims=dims, out_name=output, xsize=xsize, $ ysize=ysize, x0=x0, y0=y0, georef=1, $ out_dt=dtype, pixel_size=out_ps, $ background=-999,use_see_through=use_see_through,$ map_info=map_info output is as follows: % Restored file: ENVI. % Restored file: ENVI_M01. % Restored file: ENVI_M02. % Restored file: ENVI_M03. % Restored file: ENVI_M04. % Restored file: ENVI_M05. % Restored file: ENVI_M06. % Restored file: ENVI_M07. % Restored file: ENVI_M08. % Restored file: ENVI_D01. % Restored file: ENVI_D02. % Restored file: ENVI_D03. % Restored file: ENVI_CW. % Restored file: ENVI_IDL. % Restored file: ENVI_IOW. % Compiled module: MOSAIC_MAKER_JG_V02. % Restored file: MOSAIC_BATCH. % Restored file: ENVI_RV. % Restored file: MCTK. % Restored file: ENVI_BAT. ENVI> modis_mosaic_batch % Compiled module: MODIS_MOSAIC_BATCH. % Loaded DLM: MAP_PE. % Restored file: ENVI_MOS. The empty output file has been created. Anybody encounters this case? Who could help me? Thanks, Qingqing