Hello & Welcome to Just Answer,
Sorry I didn't see your question earlier and to hear of any issue you are having with your device.
To help you with this issue, may I ask:
1) What is the AGE of the Nuvi 2599 device?
2) WHEN was this issue first noticed and WHEN was the last time the 2599 was SUCCESSFULLY connected and recognized by Garmin Express?
3) I see that the cable has worked for other devices, but have you TRIED a different USB cable yet?
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