mmmh... this line...

system("2_CleanXMLfiles.pl \"$now_string\"");

probably I'm not understanding the question but...

1-Where is the "verb" for this line? No action here.

2-Why do you need to put the first arg to the subordinate perl script inside ""?

3-... And what args do you expect to be passed to the perl script 2_CleanXMLfiles.pl called by the main script?

I suggest you to rewrite the system line avoiding to be ambiguous, like this:

system ("VERB", "ARG1", "ARG2", ...); i.e. adjust to your needs and try:

system ("perl", "2_CleanXMLfiles.pl", "\"$now_string"\"");

If you can, avoid also to call \"ARG1\". Wrap ARG in "" directly inside 2_CleanXMLfiles.pl