CHIRP

You should ask such questions on the "mailing list":http://intrepid.danplanet.com/mailman/listinfo/chirp_users, instead of opening a bug report.
Also a debug log, as explained in How To Report Issues, would be really helpful.

Without all this it's a lot of guess work: it could be a cable / driver / connector issue. Please refer to these Wiki articles:
CableGuide
CableGuide FTDI OEM Cables
[RTSystemsCablesAndMavericks]
Windows notes: If you are using a generic cable with a Prolific chip, you will very likely need to downgrade your driver to version 3.2.0.0.
It can be found at http://www.miklor.com/COM/UV_Drivers.php
MacOS notes: this OS is apparently very picky about USB to Serial cables. From what I heard, only (genuine) FTDI-based cables can be made work.
You must have the KK7DS Python runtime for Mac OSX installed.
Also see MacOS Tips!
Linux notes: Linux generally is quite good with USB to Serial converter drivers. The most likely cause for grief is a connector which doesn't provide good electrical contact.
Bluetooth notes: connections often suffer from timing issues, please try a cable instead.

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