amount sum returning as empty string

I am trying to return a sum of invoice amounts for year to date and all I am getting returned is an empty string. I have tried three ways with both 'total' and 'amount' and just get an empty string value. The same search built in the UI returns a totaled currency value. Here is my code so far:

 // ======================================================================================  // Y T D   var ytdfilters = [];      ytdfilters[0] = new nlobjSearchFilter('type', null, 'is', 'Invoice');  ytdfilters[1] = new nlobjSearchFilter('salesrep', null, 'is', salesrepid);  ytdfilters[2] = new nlobjSearchFilter('trandate', null, 'within', 'thisfiscalyeartodate');    ytdfilters[3] = new nlobjSearchFilter('department', null,'is', 5);  ytdfilters[4] = new nlobjSearchFilter('custbody_order_type', null, 'anyof', [1,3,4]/*['Add On', 'New', 'Upgrade']*/);     var ytdcolumns = [];  ytdcolumns[0]  = new nlobjSearchColumn('formulacurrency', null, 'sum');  ytdcolumns[0].setFormula('{amount}').setLabel('ytdsum');  ytdcolumns[1] = new nlobjSearchColumn('total', null, 'sum');  ytdcolumns[3] = new nlobjSearchColumn('total', null, 'sum');           var ytdsearchresults = nlapiSearchRecord('transaction', null, ytdfilters, ytdcolumns);  if (ytdsearchresults){        var ytdsearchresult = ytdsearchresults[0];   var ytd2 = ytdsearchresults[0].getValue('total', null, 'sum');   var ytd3 = ytdsearchresults[0].getValue('amount', null, 'sum');   var ytdcolumn = null;