I am working with index() and how I am using it with Arrays is not working

foreach(@Array1)
{
        $string1 = $_;
        foreach(@Array2)
        {
                my string2 = $_;
                my $result = index($string2, $string1);
                if($result <= 0)
                {
                        print $string1, " is not found in ", $string2,
+"\n";
                }
        }
}
[download]

My @Array1[0] and $string1 is 'FFF'
My @Array2[0] and $string2 is 'FFF NNN JKK III LLL QQQ'
However my return on the above is

FFF is not found in FFF NNN JKK III LLL QQQ

Cleary 'FFF' is part of string 'FFF NNN JKK III LLL QQQ' and should return a result >= 0

This code works however when I am not using Arrays

my $string = "FFF NNN JKK III LLL QQQ";
my $substr = "LLL";

my $result = index($string, $substr);
if($result > 0)
{
        print "Result: $result\n";
}
else
{
        print "not found";
[download]

Result: 16
Is there some way I am going about my Array handling incorrect