Sometimes when you have something like this:

use DateTime::Format::ISO8601;
use DateTime::Format::Strptime;
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You need these statements before that also:

use DateTime;
use DateTime::Format; #maybe even this also
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I prefer to add use statements to the source code rather than adding options to the perlapp command.

Update: BTW I prefer the PerlApp GUI instead of the command line. Type "perlapp" with no parameters to start it.