There are a couple of reasons for this. You might have saved ou-wifi in your settings to automatically connect to this access point. This will need to be removed. Also you might have some software preventing you from connecting correctly. An example of this is the Intel pro-set wireless manager utility.
On some laptops, an Intel pro-set wireless manager utility will be installed to manage your wireless. If your computer has this utility, and you are trying to connect to the Oakwood ou-wifi network, you will need to disable this. To do this, follow the instructions provided.