Unicode::Collate string replacements and whitespace

dear all,
most probably I'm missing something quite obvious and very simple, but I am no 
expert with Perl and Unicode yet.
 I'm making some string replacements with Unicode::Collate which generally 
works fine but for whitespace. I have the following simple code (adopted from 
the module documentation):
 
 my $myCollator = Unicode::Collate->new( normalization => undef, level => 1 );
 my $str = "Camel donkey zebra camex{301}l CAMEL horse cAm