If you are having trouble logging into the Playback App you should check the following:
Which region are you trying to sign into?
At the moment the regions available are Europe, UK/Europe, Great Britain, Japan, USA, Australia, Singapore and Sandbox/Lab. You should check with your service provider to know which region you have been assigned.
Are your login details correct?
It happens because of the screen smaller on your mobile, you may accidentally type the incorrect letter to your password or username.
If you are still having problem signing into the app, please contact us here and we can assist you with this.