Set Tag for Media Entities from a Service in for loop

I have a list of entities prepared in an infotable. Looks like "Things[entityname].SetTags(params);" this code works only for things but not for media and style definition entities. Please help.

try
{

var selectedTags = INFOTABLE; \\(list of entities);

var tableLength = selectedTags.rows.length;
for (var x = 0; x < tableLength; x++) {
var row = selectedTags.rows[x];

var tags = new Array();
var params = {
tags: "TagName:Voc"
};

var entityname = row.name;
Things[entityname].SetTags(params);

}
}
catch(err) {
logger.error("Error @ Thing -"+me.name+", Myservice, @ line " + err.lineNumber + ": " + err);
}