1. Check that at least one of the doPrint variables in the ini.params file is set to 1.
2. If you have specified times on the command line, check that data exists at these times. One way to do this is to look at the inventory file for the archive file you are using. This file will have a .chansum extension and the same numerical prefix as the archive file. If the inventory file does not exist, it can be created by running inventory after setting the ARCHIVEPATH environment variable to the desired archive file.
3. Check that the fringe tracker was locked during the specified time. It is possible that data are present but the fringe tracker was not locked. To see ALL fringe tracker data, set doPrintRaw in ini.params to 1. Beware that the output volume from this mode is substantial.
Check the specification in channels.params. You may need to change the missing telemetry channels to optional. Note: These failed returns may come in the middle of the processing after the entire archive file has been seached for calibration data and the data processing pass through the archvie is begun.