I actually had this happen to me a few weeks ago, no button came up. I tried to /e salute command, and the cadets saluted back, but there was no further interaction possible. I beamed back to my ship, then went back to try again, and this time it worked properly, and has done every since then.
This character is why I don't play my Romulan any more. Tovan Khev is NOT my BFF! Get him off my bridge!