I could be wrong, but is your myscript.sh failing, and the perl error message just bogus? Try changing the $cmd3 to be
"/bin/sh $HOME/myscript.sh"
... and then try the backtick execution of the script. Also, what does the shell script put out when you execute it by itself? If the syntax looks correct, check the dependancies. Do you get any additional info by using #!/usr/local/bin/perl -w?

    --jb