You have asked a very very common question. The common answer is - Yes, you can do it. But your RC environment should have the same configuration as your QA one. That is, your application elements must have the same properties and its values in both environments.
They don't have to be the same. You can use variables and wild cards for your identification properties.
My guess is that the URL changed and there for all children can't be found.
it's probably something like www-qa.app.com and www-rc.app.com
The identification could be *.app.com if using namemapping.
