dlaine:
Yes, the application is active that understands the F11 key.
The programme takes a snapshot whenever the F11 key is pressed.
The code I used does nothing with the F11 key in the programme.
Then, it's time to add some Serial.print() statements, to confirm that the Keyboard.print() statement is being executed. I don't believe, though, that KEY_F11 is a string. I believe that there is a #define statement that assigns the name KEY_F11 a value, and it is that value that you should be sending.