From the parsing point of view it is hard to know whether the first row of an Excel file is meaningful or not. Unfortunately XLSX format is not that consistent identifying the header. If you export your Excel file to CSV format this issue will be fixed. Please read this subsection if you are using the BigML API, or from the Dashboard select the first row as the header information, as shown in the source configuration panel below. Notice these three options that let you select the header information are disabled for XLSL format.