Other than all the good replies you already got, *please* stop using Spreadsheet::ReadSXC! It served its purpuse when it was new and no alternatives were available, but it it is unmaintained and buggy (as you already noticed).

The currect best alternative is using Spreadsheet::ParseODS, which has almost the same API as Spreadhseet::ParseExcel and Spreadsheet::ParseXLSX.

You can also consider Spreadsheet::Read if you do not need writing, as it is a unifying wrapper over most supported spreadsheet parsers.