Access-Control-Allow-Origin

Hi
i have a problem! I have create a app with Ionic that connects to a external database (mysql) through a file php.

I have inserted the following lines of code in the file:

header(“Access-Control-Expose-Headers: Access-Control-");
header("Access-Control-Allow-Headers: Access-Control-
, Origin, X-Requested-With, Content-Type, Accept”);
header(‘Access-Control-Allow-Origin:*’);

but I keep having the following error

“[Error] Origin http://localhost:8103 is not allowed by Access-Control-Allow-Origin.
[Error] Failed to load resource: Origin http://localhost:8103 is not allowed by Access-Control-Allow-Origin. (retrive_data.php, line 0)
[Error] XMLHttpRequest cannot load /app_es/retrive_data.php due to access control checks.”

Can someone help me, thanks!

Erika