I don't know about that.
Could be that the external enclosure you bought isn't supplying enough voltage to the LiteOn burner, some burners require less, the LiteOn & Plextor require the most (from what I've read on The big external enclosures thread).
I'm using the newest Prolific chipset on a Bytecc ME-340U2F (pretty aluminum case), and have had the following drives in perfect working order w/ it...
NEC ND-3540A, Plextor PX-716A, LiteOn 1653s & 1693s.
Only prob I was having, is that the burning speed topped out @ 15.93x, but maybe that isn't such a bad thing, it only added 8-12 seconds to each 16x burn.
The prolific firmware I'm using is "fw ver.2004.12.09.200"