Simple (Hopefully) Suitelet question

Hello,

I am trying to create a suitelet that will split an SO.

I would like it to run through the following steps:
- Enter SO
- Display item lines from that SO with tick box to indicate lines to split out
- Goes away and copies SO removing ticked lines from original and retaining only those lines on the copy

The last bit i have done and am happy that it works, its the displaying that i am having trouble with.

I have done this:

function SplitSOSuitelet(request, response)  {   if ( request.getMethod() == 'GET' )   {    var form = nlapiCreateForm('SO Split');    var filters = new Array();    var columns = new Array();    var soToSplit = form.addField('custpage_sotosplit','select','Select Sales Order','transaction');      var soItems = form.addSubList('custpage_soitems','list','Lines to split');    soItems.addField('sublist_item','text','Item');    soItems.addField('sublist_qty','float','Quantity');    soItems.addField('sublist_desc','text','Description');    soItems.addField('sublist_split','checkbox','Split');      filters[0] = new nlobjSearchFilter('type', null, 'is', 'salesOrder');    filters[1] = new nlobjSearchFilter('tranid', null, 'is', 'SO42140');    filters[2] = new nlobjSearchFilter('mainline', null, 'is', 'false');      columns[0] = new nlobjSearchColumn('item');    columns[1] = new nlobjSearchColumn('quantity');    columns[2] = new nlobjSearchColumn('description', 'item');      nlapiLogExecution('DEBUG', 'Filters', filters[0]+filters[1]+filters[2] );    nlapiLogExecution('DEBUG', 'Columns', columns[0]+columns[1]+columns[2] );      var itemsdata = nlapiSearchRecord('transaction', 4936, null, null );      nlapiLogExecution('DEBUG', 'Data', itemsdata );      soItems.setLineItemValues( itemsdata );      form.addSubmitButton('Split');