I'm experiencing the same as you:
2012-12-03 16:03:00 The Beijing Courierpost bulk mail acceptance center Acceptance
2012-12-03 16:08:00 The Beijing Courierpost bulk mail acceptance center Leave the treatment center, sent to Beijing
2012-12-03 18:54:03 Beijing The arrival processing center from the center of the Beijing Courierpost bulk mail acceptance
2012-12-04 02:12:09 Beijing Leave the treatment center, sent to Brussels
2012-12-04 19:36:09 Beijing The arrival processing center from security checks returned
2012-12-05 01:56:38 Beijing Leave the treatment center, sent to Brussels
2012-12-06 19:36:53 Beijing The arrival processing center from security checks returned
2012-12-06 20:57:11 Beijing Leave the treatment center, sent to Brussels
Looked around a bit on the web and found this:
Tracking Skills - Taobaoring.com
"Repeated shows "Despatch from Sorting Center" means your parcel is returned by security check. But why? my parcel only include normal items like pants or T-shirts. The answer is simple: your parcel is filled into a big parcel(mixed with others parcels) to checked, if one the them are not pass the security check, all them will be returned to original post office.
If your parcel include some unsafe items like battery, liquid or brand items without formal invoice, it maybe confiscated or destroyed by Customs."
Let me know how it turns out with your orders! Good luck!