Please note that Pleiades data is directly supported in Geomatica 2016. This means that you can open the image in Focus using the DIM file. This error is usually caused by an issue with the input parameters. ATCOR extracts the gain and offset parameters from the raw data. Please make sure that you are using the Pleiades DIM file as the input for ATCOR. If you are using this file, the radiometric data (gain/offset) values in the image may be missing or the image may have too much cloud (90%). To check for the presence of these parameters, open the properties for each individual raster of the raw dataset. If there are no gain and offset values then the default calibration file for Pleiades imagery is used. The calibration file provided in Geomatica is generalized for all Pleiades data and is not specific to any exact dataset.