In order to solve the issue, open your device, navigate to Settings > All > Apps/Applications, tap SMS Leb - MTC Touch Support icon and clear all data and cache. After that, try again to log in. If it doesn't work, remove the software and download and install the updated version from Google Play Store. If you still have issues, it's possible that SMS Leb - MTC Touch Support servers are temporarily down or under maintenance. In this case, you will need to wait. For further information, I suggest you use
firstname.lastname@example.org to get in touch with the developer.