Hey, here is fixed code 
[CODE=javascript]var doc = app.activeDocument;
//SAVE RULER UNITS
backupRuler = app.preferences.rulerUnits;
//SET RULERS TO PX
app.preferences.rulerUnits = Units.PIXELS;
//SET POSITION OF SAMPLE
var xPos = 5;
var yPos = 5;
//REMOVE EXISTING SAMPLES
app.activeDocument.colorSamplers.removeAll();
//SET NEW SAMPLE
var target = [xPos , yPos];
var sample = app.activeDocument.colorSamplers.add(target);
//GET COLORS FROM SAMPLE
var Color = sample.color;
var R = Math.ceil(Color.rgb.red);
var G = Math.ceil(Color.rgb.green);
var B = Math.ceil(Color.rgb.blue);
//REMOVE SAMPLE
app.activeDocument.colorSamplers.removeAll();
//SET NEW COLOR
var color = app.backgroundColor;
color.rgb.red = R;
color.rgb.green = G;
color.rgb.blue = B;
app.backgroundColor = color;
//RESTORE RULER SETTINGS
app.preferences.rulerUnits = backupRuler[/CODE]
