The mame rom path (for retropie 2.3) is /home/pi/RetroPie/roms/mame
That /home/pt/ directory is odd – it should be home/pi
That implies your user is wrong hence having permission issues.
Have you got a fairly clean install like this?
Actually – your path implies you are using an older version of RetroPie – I’d be tempted to run 2.3 instead?