Mismatch: X:1451 doesn't match requested X:1450
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-6478-Polka.ps) >>/Users/jc/w/tmp/Tune-6478-get.log 2>&1" returned status 256
http://michel.bellon.free.fr/Musique/abc/Nouveau/Polka.abc

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 PNG]
filesizedescription
Tune-6478-Polka.abc 913 ABC music file with the extracted tune(s)
Tune-6478-Polka.ps 45702 PostScript
Tune-6478-Polka.txt 913 Plain-text file with the extracted tune(s)
Tune-6478-get.log 800638 Log file, useful mostly for debugging
These files should be available for 24 hours.