The issue is that readdir() returns just the file/dir name in the target dir so you need to add the dir path to your -d test

 
if ( -d "$dirtoget/$f" )
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You could of course just do this:

# dirs with full path
print "$_<br>\n" for grep{ -d $_ } glob($dirtoget);

# just the relative path
print "$_<br>\n" for map{s/\Q$dirtoget\E//;$_}grep{-d $_}glob($dirtoge
+t);
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map grep and glob are useful perl power tools....