How to test whether a drop down box is empty

Good evening I am attempting to create large if-then structured built into Functions.

However, I am running into the problem of not being able to write IF-ELSE statements, when the argument is whether a drop-box is empty, or not.

Here is an example:

var dropBox = this.getField("Drop Box)";
var SourceField = this.getField("Source");
if (dropBox.valueAsString != "") {
  console.println(sourceField);
}

Even if Drop Box has no strings selected, it still won't complete the statement.

Any help would be greatly appreciated!