Right - but does RX?
unipi_plc is only on the beta image, apologies
And I would try Mervis if possible. It has drivers done via a different library, and has better debugging facilities. Though if the RX light does not turn on Mervis won't be able to do much - it will just display constant timeouts.
e: More specifically no RX light means that there are no replies, TX light simply means that something is sent, regardless of whether the settings are correct or not.