Cannot synch to folders that were previously used for synchronization

Hi,
My systems has two disks: One system disk and one Data disk. I recently reinstalled win8 on my system disk and tried to make new synchronizations with TI2013 between the Data disk and an external disk. But True Image refuses to synch to them and tells me that they are already part of a synchronization. What to do?
I guess that TI stores some information about synchronization inside the synch folder but what and where???

Thanks in advance,

Joost