getCurrentBarIndex is always -1, How do I get it to be 0 (zero)?

[WantToLearn]

I downloaded the program called "BidAskVolume" and ran it. It will only give me the total volume and not the bid or ask volume. I narrowed it down to the statement that is causing the problem:

if (getCurrentBarIndex() < 0) return;

it appears that getCurrentBarIndex is never 0, it is always -1. What am I doing wrong?

The program is below:

function preMain() {
    setStudyTitle("Bid\/Ask Volume ");
    setCursorLabelName("Ask Vol", 0);
    setCursorLabelName("Inside Vol", 1);
    setCursorLabelName("Bid Vol", 2);
    setDefaultBarFgColor(Color.green, 0);
    setDefaultBarFgColor(Color.black, 1);
    setDefaultBarFgColor(Color.red, 2);
    setDefaultBarThickness(4, 0);
    setDefaultBarThickness(6, 1);
    setDefaultBarThickness(4, 2);
    setPlotType(PLOTTYPE_HISTOGRAM, 0);
    setPlotType(PLOTTYPE_HISTOGRAM, 1);
    setPlotType(PLOTTYPE_HISTOGRAM, 2);

    var fp0 = new FunctionParameter("sType", FunctionParameter.STRING);
        fp0.setName("Analysis");
        fp0.addOption("Bar");
        fp0.addOption("Cumulative");
        fp0.setDefault("Bar");
}

var nBidVol = 0;
var nInsideVol = 0;
var nAskVol = 0;
var vVol = null;
var bPrimed = false;
var nAsk = null;
var nBid = null;

function main(sType) {
    if (getCurrentBarIndex() < -1) return; // ******  This is where the problem is?  ******
    var nState = getBarState();    
    if (nState == BARSTATE_NEWBAR) {
        if (sType == "Bar" || day(0) != day(-1)) {
            nBidVol = 0;
            nInsideVol = 0;
            nAskVol = 0;
        }
        vVol = 0;
    }
   
    var vPrevVol = null;
    if (vVol != null && bPrimed == true) vPrevVol = vVol;
    
    var nTempAsk = getMostRecentAsk();
    var nTempBid = getMostRecentBid();
 
    if (nTempAsk != null && nTempAsk != 0) nAsk = nTempAsk;
    if (nTempBid != null && nTempBid != 0) nBid = nTempBid;

    var vClose = close();
    vVol = volume();
    
    var vTradeVol = vVol - vPrevVol;
    
    if (bPrimed == false && vVol != null) {
        bPrimed = true;
        return;
    } else {
        if (vClose <= nBid) {
            nBidVol += vTradeVol;
        } else if (vClose >= nAsk) {
            nAskVol += vTradeVol;
        } else {
            nInsideVol += vTradeVol;
        }
    }

    return new Array(nAskVol, nInsideVol, nBidVol);
}