Fora Test N'GO Advance Pro Owner's Manual page 34

NOTE:
 While the meter is in transmission mode, it will be unable to perform a test.
 Make sure that your Bluetooth enabled device has turned on the Bluetooth
signal prior to transmitting the data, and that the meter is within range.
 For OS version requirements please refer to the App description on the Apple
App Store or Google Play Store.
 A compatibility issue between your mobile device and the meter might occur
due to the way Bluetooth functionality is implemented by the various mobile
device manufacturers.
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