We are currently working on every single device to make them work perfectly with Perifit.
First of all, try to update your Perifit app, this might solve your connection issue (go to the App Store or Google Play Store and look for Perifit).
If updating the app did not solve your issue, use the email button inside the Perifit app and send us an email with it. This will allow us to see what is going wrong with the Bluetooth connection. We will get back to you within 24h.