Variables plot on chart but not on WatchList

[pj909]

It appears as though the watch list doesn't like the fact I'm looking a price study and also calling an indicator (Acc/Dist) in the script.
Everything looks fine on a chart but the WatchList columns just have a little green square - no data.
I'm using the Acc/Dist to confirm the direction change (the intermediate steps aren't shown) and change the nBarCnt accordingly.
The purpose is to use the nBarCnt value in a WatchList to see what symbols had triggered a direction change.

debugClear();
var fpArray = new Array();

function preMain() {

    setPriceStudy(true);
    setStudyTitle("test");
    setCursorLabelName("HiAvg",0);
    setDefaultBarFgColor(Color.blue,0);
    setPlotType(PLOTTYPE_LINE,0);
    setDefaultBarThickness(1,0);
    setCursorLabelName("LoAvg",1);
    setDefaultBarFgColor(Color.red,1);
    setPlotType(PLOTTYPE_LINE,1);
    setDefaultBarThickness(1,1);
    setCursorLabelName("TradeBars", 2);
    setShowSeries(false, 2);
    setDefaultBarFgColor(Color.khaki, 2);

    var x=0;
    fpArray[x] = new FunctionParameter("LLen", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(8);
    }
    fpArray[x] = new FunctionParameter("HLen", FunctionParameter.NUMBER);
    with(fpArray[x++]) {
        setLowerLimit(1);
        setDefault(10);
    }
    fpArray[x] = new FunctionParameter("Params", FunctionParameter.BOOLEAN);
    with(fpArray[x++]) {
        setName("Show Parameters");
        setDefault(false);
    }

}
var grID = 0;
var bInit = false;

var xMAlo = null;
var xMAhi = null;
var nL = 0;
var nH = 0;
var nWidth = 0;

var xAD = null;
var xMA = null;
var nAD = null;
var nMA = null;


var nBarCnt = 0;

function main(LLen, HLen, Params) {

    if(bInit == false){
        xMAlo = sma(LLen, low());
        xMAhi = sma(HLen, high());
        setShowTitleParameters(eval(Params));
  xAD = accDist();
  xMA = sma(57,xAD);
        bInit = true;
    }

 // get the current Acc/Dist and direction
    nAD = xAD.getValue(0);
    nMA = xMA.getValue(0);
    if (nMA == null || nAD == null) return;

    nL = xMAlo.getValue(0);
    nH = xMAhi.getValue(0);
 if (nL == null || nH == null) return;

/*

do some stuff

*/

 if (close() > nH) {
  (nBarCnt <=0) ? nBarCnt = 1 : nBarCnt++;
 } else if (close() < nL) {
  (nBarCnt >0) ? nBarCnt = -1 : nBarCnt--;
 } else {
  nBarCnt = 0;
 }


    return new Array(nH, nL, nBarCnt);
}