When you created the folder.. you didn't create it inside a sparsebundle?? You created it directly in the main root directory of the TC?
Login with the same user name and same credientials and from the same computer as you used to create it.
No luck.. reset the TC to factory settings.. this will simply remove any user permissions issues.. and leave all the settings at default and look again.
Strangely have a look from windows.. rather than Mac OS.. things suddenly do appear when you access them via SMB instead of AFP.
You will need to use v5 utility.. on the disk page..
If you have lion you directly download it.. if ML follow these instructions to install.
How to load 5.6 into ML.
1. Download 5.6 for Lion.
Click to open the dmg but do not attempt to install the pkg.. it won't work anyway.
2. Download and install unpkg.
Run unpkg on the desktop.. it is very simple.. drag the AirPortUtility56.pkg file over to unpkg.. and it will create a new directory of the same name on the desktop.. drill down.. applications utilities .. there lo and behold is Airport utility 5.6 .. drag it to your main utilities directory or just run it from current location.
You cannot uninstall 6.1 so don't try.. and you cannot or should not run them both at the same time.. so just ignore the toyland version.. the plastic hammer.. and start using 5.6.. a real tool.