Sorry about a late reply - this is very hard to troubleshoot without details but in general, the localizations have some specific quirks to work around - for the legacy tax it is e.g. inability to deal with multi-currency or deviating base currencies, for suitetax you may have more advanced 'quirks'.
The documentation is usually quite good in terms of denoting what type of tax code goes into what box - you have to go backwards from there, pull reports for the codes to be summed up in one of the boxes and try to nail what is missing / wrong. Following that you may need help from Netsuite support - suitetax is still 'new' so there are most certainly bugs.