If you are testing for a specific workload and want to determine database statistics related to that workload you may wish to use just the raw statistics, we tried using snapshots and there is a limit, even pulling 5 minute snapshots on a modern 2 socket system produces a sequence error in the ttStats package so you have a limit there that can not be easily crossed.
Instead just use the raw output and redirect the files and use them as such.
Can you provide a copy of the sequence error you saw from ttStats, and some details on how you were running it? I haven't been able to find a known bug which reports this as a symptom.
There are limits to, for example, how many snapshots you can store, but these are configurable - for example, from the Docs:
Specify a limit of 500 stored snapshots:
call tt_stats.set_config('MAX_SNAPSHOT_COUNT', 500);