How to execute mpg123 at given time with at

I was testing few things, nothing is working. I have this command called ~/bin/beep for sound notifications.

#!/bin/bash

mpg123 -q /home/kuba/Pobrane/beep-6.mp3

I usually use it like this:

sleep 4m && beep

and I'm trying to execute it at the give time with at. I was testing by specifing next minute. I was trying:

at 14:01  /home/kuba/at.log

No error, no sound. How should I execute mpg123 with at?