Note that permissions on all of the ancestor directories also matter.

To aid in diagnosing the problem, you might want to do something like the following:

my $dir = '/home/bla­/public_ht­ml/blabla'­;
my $isDir = -d $dir;
if(  $isDir  ) {
    print "Found directory: $dir\n";
} elsif(  defined $isDir  ) {
    print "Found non-directory: $dir\n";
} else {
    print "Can't stat($dir): $!\n";
}
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That way you can distinguish between "permission denied" vs "no such file/dir" vs something more exotic. The next step narrows down the source of the problem:

use File::Basename 'dirname';
my $dir = '/home/bla­/public_ht­ml/blabla'­;
my $isDir;
while(  ! defined $isDir  ) {
    my $isDir = -d $dir;
    if(  $isDir  ) {
        print "Found directory: $dir\n";
    } elsif(  defined $isDir  ) {
        print "Found non-directory: $dir\n";
    } else {
        print "Can't stat($dir): $!\n";
    }
    last
        if  '/' eq $dir;
    $dir = dirname( $dir );
}
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