troubleshooting guide

Is there any troubleshooting guide for when the stats don’t show in the dashboard? I’ve tried this on two sites. On one site the stats loaded instantly. On another site no stats (this site has less web traffic). Both sites are hosted on the same server.

Is there a minimum amount of traffic for the dashboard to work?

Is there a way to force a refresh or for stats to compile rather than waiting 24 hours? Also why would it take 24 hours – is it somehow dependant on your server or something?