I know it is not the answer to your question, but it is generally a bad idea to work with shape names.
Those named shapes could be deleted, moved to another page, just to name some of the problems.
You're better off by defining a certain property - eg a user or a prop field - and set its value to an arbitrary unique id (eg chosen by yourself).
To work with that shape, you would iterate over the shapes of the page and check for the existance of the property and its value.
I Hope the explanation is somewhat comprehensible.