"at" command does not run desired program / script

I am trying to learn scheduling with the "at" command, and therefore, I want to test it out and keep things simple. For example, when I type "at 00:28" (my time zone's format), and then enter /usr/bin/leafpad, I expect leafpad to start at 00:28. That does not happen though. Nothing happens, basically. When I check the related job id with "at -c jobid", the tail of it says "Execution directory inaccessible". That's pretty weird, because when I type in "/usr/bin/leafpad", leafpad actually opens up. I am using Kali Linux btw.