In Q2 2013 we have added a new property for RadMenuItem - InputGestureText. This text is populated automatically if your command has key-gesture, but you can also set it as a string. More information is available in our online help.
Before that RadMenuItem didn't support automatically populating of the KeyGestures, so maybe you have used a custom template. If this is the case I suggest you to try our latest release and remove the custom template if everything is working fine.
Hope this helps.
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