Online reports said the ` ` ' '' were unable to perform in Serbia . The Serbia concert was suppose to kick off a 12-date European tour . Winehouse entered a rehab facility last month to prepare for the tour .
Online videos show the `` Rehab '' singer unable to sing in Belgrade . The Serbia concert was suppose to kick off a 12-date European tour . Winehouse entered a rehab program last month to prepare for the tour .