Browser Compatibility issue in isc.sortObjectByProperties(cpValueMap)

I am using isc.sortObjectByProperties(cpValueMap); method to sort my valuemap object by its value (not by id).

Its working fine in FF and safari but in IE and chrome it is sorting still on basis of ID .

Then I use a custom method but still giving same result as mentioned above .

my custom method :>>>

function sortValueMap (map) {
var mapValues = isc.getValues(map);
mapValues.sort();
console.log(mapValues.sort());
var newMap = {};
for (var i = 0; i < mapValues.length; i++) {
newMap[isc.getKeyForValue(mapValues[i],map)] = mapValues[i];

}
return newMap;

}

Note : I am using latest version of all these browsers and using window7 as OS. Please help its urgent