Make sure that you configured the frequency and modulation correctly by going to Main Menu → Sub-GHz → Read → Config.
You can determine the remote’s frequency by using the Frequency Analyzer. To do that, go to Main Menu → Sub-GHz → Frequency Analyzer. You can also look up the device’s FCC-ID to find information about frequency and modulation.
If you see the lock icon after reading a sub-1 GHz radio signal with the Read function, it means the captured signal has a rolling code that Flipper Zero can’t save.
If you are unable to transmit a saved signal at a sub-1 GHz radio frequency, it may be due to a frequency restriction for civilian use in your region, as indicated by the Table.