Trend Strength Indicator - Hellp

[BB]

Could some one help me in fixing the following efs code:

var xRatio, xResult

function preMain(){

setPriceStudy(false);
setStudyTitle("TrendStregthIndex");
setShowTitleParameters(false);
setShowCursorLabel(true);

}

var xRatio = false;
var xResult = false;


function main() {


xRatio[0] = Math.abs((close() - (close(-10))) / atr(10));
xResult = sma(sma(xRatio, 10), 100);

return xResult;


}

---
Error message received is:

line21: Parameter umber 1 of Function sma is invalid.
line21: cant't convert sma(xRatio, 10) to an integer.

Sample of efs is as per the attached /shown below file.