This is usually an easy fix (update your database within the app) or a temporary issue (FAA website down, something with your ISP, etc).
SimPlates feeds you with USA plates directly from the FAA's website. As such, these are a different from non-USA plates in SimPlates, which come from our own servers.
If USA plates aren't loading, make sure that you have the latest SimPlates database. If you're sure you do, please wait a day or so and try again.
If you're sure you have the latest database and have waited sufficient time, try rebooting your PC. Sometimes the issue for some users have been DNS issues at their ISP. Rebooting can often fix this.
Sometimes, the FAA site may be down temporarily. Waiting a while and trying again fixes this.
Sometimes, the FAA changes their data formats. They do this about once every few years. If you have tried all of the above and it's still not working after a few days, please let us know. We'll try to fix this, though please be advised that fixing this is often a multi-day project that we need to schedule internally, so we thank you for your patience should this be necessary.