There are different ways of accessing the RadToolBar from code behind. Basically, it depends on your implementation set-up. One way is to use the Items collection of the RadToolBar and directly get the desired button. I have created a sample project which demonstrates how you can enable a button in the toolbar on the selection changed of the RadGridView.
The project is attached to this reply. Give it a try and let me know if it works for you. If not, can you elaborate more on your application set-up?
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