my $ptf_filename;
    ...
    if ( $response->is_success ) {
        ...
        my $ptf_filename = $data->{PtfFileName};
        ...
    } 
    return $ptf_filename;


##</code><code>##

>perl -wMstrict -le
"my $x = 1;
 my $x;
 print $x;
"
"my" variable $x masks earlier declaration in same scope at ...
Use of uninitialized value $x in print at ...