If you're seeing unscheduled games – either NOT YET SCHEDULED or NO POSSIBLE TIME SLOTS – that's typically because of constraints or because you don't have enough time slots to fit all your games.
You can try iterating (i.e. hitting retry allocating games and if that doesn't improve things erase games and re-generate the whole schedule – this will give you new pairings, which may or may not unclog things).
You can also lock weeks that are fully allocated > retry allocating > see if any more weeks got fully allocated > lock those > repeat. (It can take several attempts to get before another week is fully allocated. If you see no progress after 5-10 attempts, you should consider a different approach.)
Note that, for leagues, allocating games does not move the games outside of the weeks they are in. If you see NO POSSIBLE TIME SLOTS, no amount of reallocations will help. You may want to manually move those games to other weeks and then retry, or just manually put them somewhere and override the constraint warning.
In some cases, using the tournament scheduler is a better solution when your time slots are not evenly spread across weeks or certain teams can't play in certain weeks. The tournament scheduler is not bound by weeks, so that added flexibility can help. If you'd like to try this approach, please reach out to us and we can switch your schedule to tournament mode, so you don't have to start over. Note that this might require some other tweaks (e.g. setting minimum time between games to a few days to make sure any team's games aren't bunched together).
That's the process more or less. Unfortunately, our system is not magic – so some trial and error is involved and certain scenarios just might not work. Let us know if you have any questions about all of this or if you'd like to engage our services under our full service agreement and have us take a stab. We can't guarantee a solution in these cases unfortunately – we can only do the same things described above; some schedules can be too complex to solve or may require large amounts of manual work, which we may or may not have the bandwidth for (and either way, we'd let you know before going down the rabbit hole) – but we can definitely try all the normal things and let you know where you're at.