If you get data that just won't behave when viewing the data using the custom file format, a possible cause is the file extension. If this is set to .csv (a common excel format - comma separated values), it causes no tab to appear between data points if you have the field delimiter set to tab. The symptom being that entire data strings fall into a single cell. The remedy in this case is to change the field delimiter to a comma. Excel then replaces the commas with tabs and the data flows properly. (An alternate solution is to change the file extention to .it8 and leave the field delimiters as tabs.)