I have a site for self-registration which calls Site.createPortalUser()  to create a new portal user if it is a new user. It works perfectly on site registration page. The problem now is that I have to capture facebook login and create portal user for facebook users. Current code has callout function to get facebook user's email, userid and username, etc. And then, pass those info to the same function used for site registration page. All parameters are correct, just don't know why Site.createPortalUser()  always give me null userId? Anyone has any idea about this?

I have a site for self-registration which calls Site.createPortalUser()  to create a new portal user if it is a new user. It works perfectly on site registration page. The problem now is that I have to capture facebook login and create portal user for facebook users. Current code has callout function to get facebook user's email, userid and username, etc. And then, pass those info to the same function used for site registration page. All parameters are correct, just don't know why Site.createPortalUser()  always give me null userId? Anyone has any idea about this?