In case You have issues with registration or login please follow instructions below.
Please clear YunGO application data and cache. Start YunGO application again and try to re-register.
How to clear application data and cache.
To do this, head to the storage section of Settings on your device. In 4.2 and up, you'll see a new item called "Cached data". Tapping this will give you the option to erase everything. Please tap also "Clear Data" item.
While this may have some unintended effects like making things take longer to load or forcing you to re-login to apps, it can help performance to do so once in a while.