If you're not receiving 6 code from Facebook, there could be several reasons for the issue:

1. Network Issues: Your phone's network might be weak or unstable, causing delays in receiving SMS messages. Ensure you have a strong signal and try restarting your phone.

2. Incorrect Phone Number: Double-check that the phone number registered with your Facebook account is correct, including the country code. A typo or outdated number could prevent you from receiving the code.

3. Service Provider Issues: Sometimes, your mobile carrier may experience delays or problems with their SMS service. In such cases, you might need to contact them for assistance.

4. Spam Filters: Your phone might mistakenly filter Facebook's SMS as spam or block it. Check your spam or blocked messages folder.

5. App or Software Issues: If you're using a third-party app for messaging, such as Google Voice or WhatsApp, it might not handle SMS messages properly. Try switching to your default SMS app.

6. Too Many Requests: If you've requested the code multiple times, Facebook might temporarily block sending codes due to security concerns. Wait a while before trying again.

7. Facebook Server Issues: Occasionally, Facebook itself may experience technical problems. Check online forums or Twitter to see if others are facing similar issues.

If none of these steps work, try using an alternative method to verify your account, such as via email, or contact Facebook support for further assistance.