Hello ASIF, The SPOT 5 imagery you have received is not in it's original data format it seems so it may not have all the metadata associated with the original file. It is hard to know what processing, if any, has already occurred on the file so it is difficult to give advice on how to process it. In any case, Quac needs to know the wavelengths of each band in order to process the file. If the bands do not already have wavelength metadata, you will need to define it using Edit ENVI Header->Wavelengths. Here you can enter the band center wavelengths as needed and then save the header. Then you can run Quac.