When clicking "Map Fields" for a DAT file import, either:
1) An error appears instead of the field mapping; The error message is:
"File contains header but no valid record"
2) The field mapping dialog appears but the dialog is empty, and the error above is thrown in the "System Log".
1) Verify that the proper delimiters have been selected.
2) Verify that only one key identifier field is present in the header line.
The "Map Fields" logic will attempt to auto-map fields named "Begdoc" and "Docid" to the "Docid" field, and it is best that only one of these fields is present in the header line.
E.g. If both "Begdoc" and "Docid" fields are in the header line, then rename one of the fields.
3) If the delimiters are correct and there is only one key identifier field defined in the header line, then the error could be caused by a mismatch between the number of fields in the field header line, and the number of values in the record definition lines.
E.g. if there are 25 field names in field definition line 1, but 26 field values in the subsequent lines (lines 2 and beyond), then the "file contains header but no valid record" error will appear.
Tip: For this scenario, count the number of field separators on the header line, and compare with the number of field separators on other lines.