How are you trying to do this (e.g. via the app, website etc.)? What happens? Any error messages? If you are using the app then try the website or vice versa to see if the other works. If all else fails you'll need to contact 48 support. See the link in my signature below.
Hope this helps.
I am not a 48 employee so if you need to contact 48 support then use option 3 or the chat facility here.