The messages you've quoted do NOT support your supposition that "the problem is that it needs to use the NCBI BLAST installed components, which it cannot find." They address themselves solely to what choroba pointed out: that the first use of each needs to be declared with a "my" as, for one possibility,
in reply to BLAST and BioPerl
my ($blast_obj, $seq_obj, $report_obj, $result_obj);
If Perl couldn't find something you tried to use, it would have provided an additional message specifically stating that it can't find it (by name).