Hi,
are you using W1 NAV release ?
tried with Italian localization rollup 1 hotfix and all works fine; in my downloaded application hotfix "CalcSalesTaxLines" is not a variable loaded by 35764 patch (Rollup 1).
Try to remove 414 codeunit, reimport new 414 codeunit from hotfix (create object), try to complie and after remerge with you currently customizations.