There could be a few reasons for this, please ensure you have checked the below via your Dashboard.
You have selected the correct country
You have not entered the country code again into the box, as this pre populates automatically
You have not entered any symbols, spaces or dashes into the phone number field
If all of this has been done, and saved correctly you should receive a text code within 5 minutes, to enter onto the site, to verify your telephone number.
If you experience further issues, then please contact The Membership Services team via email, phone or live chat, who can help you further