'$' not displayed for Custom column price

Hi ,
I am using this piece of code to customize price

function eXcell_price(cell){
if (cell){
this.cell = cell;
this.grid = this.cell.parentNode.grid;
}
this.setValue=function(val){
if (val >= 0){
this.cell.style.color = “green”;
}else{
this.cell.style.color = “red”;
}
this.cell.innerHTML = this.grid._aplNF(val, this.cell._cellIndex);
}
}
eXcell_price.prototype = new eXcell;

But in doing so , the ‘$’ is not getting displayed along with the values.
Could you pls help ?