SLiM gives "failed to execute login command", kdm works fine

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https://bbs.archlinux.org – Just as a disclaimer, I'm brand-new to Arch linux.  I installed Arch this morning after using linux mint for some time.  Anyways, I wish to use SLiM as my login manager, but whenever I try to log in (whether it be root or my typical user) it says "failed to execute login command", then flashes a black screen and takes me back to an empty "Login:" box.  I used systemctl disable slim.service and then systemctl enable kdm.service and upon reboot am able to login perfectly fine.  I feel like I'm missing something fairly obvious, so any help is appr (HowTos)