Using R > Console > Execute Selection I get this:
152:163: execution error: System Events got an error: NSReceiverEvaluationScriptError: 4 (1)
Did you check this:
System Preferences > Universal Access 'Enable access for assistive devices' = true
I had the same error. By changing that System Preference item every Applescript (also be used in R > Console > Execute Line) is working well.
-Hans