Hey Piston,
I am sorry for the delay of this reply,
It seems like Facebook already changed their code so we can't use this way to get Facebook profile id
http://graph.facebook.com/{user-name} and it will throw an error:
{
"error": {
"message": "(#803) Cannot query users by their username (ericwong)",
"type": "OAuthException",
"code": 803,
"fbtrace_id": "APVE5YDWzWd"
}
}
Can you try put your Facebook profile URL in this webpage ->
https://lookup-id.com/ and see is it can get correctly of your Facebook profile id?