This is what I wrote in July 2003.
Bix's composition "Candlelights" (with an s) was copyrighted on August 29, 1929. It was played by Lennie Hayton and Arthur Schutt in the Camel Pleasure Hour broadcast of September 3, 1930.
When I first read the PS in Bix's letter of March 4, 1931, I thought perhaps he could be referring to a more recent Camel Pleasure Hour program where "Candlelights" might have been performed. [This is Jean-Pierre Lion's hypothesis, a reasonable possibility.] On the othe hand, Bix refers to a "Candlelight" (no s) program. However, Bix was a terrible speller. So all this is totally inconclusive.
I looked through a whole bunch of internet sites dedicated to "Old Radio" but found not a single mention of a "Candlelight" program.
This may be another of the unsolved mysteries in Bixology.