Hello Dwayne Moore,
RadListBox does not support client-side binding via WebServices/PageMethods out of the box. This means that you cannot bind it on the client and a postback is required. The same applies to SqlDataSource. It is tightly connected with the ASP.NET postbacks paradigm and you can hardly use it in other scenario.
A possible way to overcome this issue is enlisted below:
1) Create WebService that returns the data you need in JSON format.
2) Parse the JSON on the client
3) Create RadListBoxItems that utilize the received data
4) Add the newly created items to the listbox.
Items can be created on the client the following way:
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