Hello, i just discovered collating sequence in regex in php but it not working for me

Question

This is the error: Warning: preg_match(): Compilation failed: POSIX collating elements are not supported at offset 0 in C:\xampp\htdocs\test.php on line 73

This is the code:

$string = "AishahAishahAishah, RukoyyahRukoyyahRukoyyah and KafayahKafayahKafayah";
preg_match("/[.Aishah.]+/", $string, $array);
print_r($array);