pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-98851-Graded2.ps) >>/Users/jc/w/tmp/Tune-98851-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/SCD/Graded2.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Tune-98851-Graded2.abc 58538 ABC music file with the extracted tune(s)
Tune-98851-Graded2.ps 520261 PostScript
Tune-98851-Graded2.txt 58538 Plain-text file with the extracted tune(s)
Tune-98851-get.log 48232 Log file, useful mostly for debugging
These files should be available for 24 hours.