WARN DefaultSDFReader No valid data header found:

WARN      DefaultSDFReader                   No valid data header found:

This error message has nothing to do with the header information in the SDFile. This error message appears if an empty line is missing or if there are too many empty lines in the SDFile.


This is exactly what the warning message tells you: instead of a new data header (according to the Molfile specification the the "properties" of an Molfile are separated into "data header" and "data", terminted by a blank line) something unexpected has been found, in your case additional empty lines.