Raster resolution

Hi, I'm trying to create a script that will rasterize an object with certain resolution, but to no avail, what am I doing wrong, can anyone give me a hint?

#target illustrator

function rasterItem() {

    var sourceDoc = app.activeDocument;

    var currentItem = sourceDoc.pathItems[0]

    var resolucao = rasterizeOptions.resolution = (resolution / 72) * 400;

    currentItem.selected = true; 

    activeDocument.rasterize( currentItem, currentItem.visibleBounds, resolucao ); 

} 

rasterItem();