I don't know how to post the answer to the discussion group correctly so I just sent this to you. I got the same errors. I can write a wav file, I can play the wav file using any other audio player but GNUradio "wav source" block gives me the same " no samples.." error. I got around this by using the "File Source" and "File Save" blocks using *.wav as the names. It seemed to work.
Tom S.