My Sync Code is not Working!

I have the same account in my mobile and my computer. I just installed windows in my pc. Now when i am clicking the sync button after inputting the code, it says “This code is invalid” in red. But i am giving the exact same sync code from my phone.
I have faced this issue many times. I have to open a new sync code every time i install windows. And my previous saved things just get vanished. Can anyone tell me the issue here? or any technical support?