In the beginning same problem was with me in referral program of WCEX but later on i comes to know what exactly is the problem. When i send link to my friends , they open it and it opens in Native language (Hindi in my case) and they change it to English. When they change language, referral link will not work and you will not get coins of your referral sign up.
If they will sign up without any change in language then we get Tokens from referral.
Thank you