How do you handle a UIPickerView in UI Automation iPhone application testing?

Question

In the following UI Automation script code, I'm able to get the values from a UIPickerView, but I'm not able to select the picker:

var picker = window.pickers(); 

UIALogger.logMessage("picker array count: " + picker.length);

var pickerWheels = picker[0].wheels();

UIALogger.logMessage("picker Wheel count: " + pickerWheels.length);

var pickerWheelsValues =pickerWheels[0].values();

UIALogger.logMessage("picker Values count: " + pickerWheelsValues);

pickerWheels[0].values()[0].tap();

What might I be doing wrong?