Stop Scanning

The equipment start normally without any error, warning and service message. When I put the phantum for QC and start scan, equipment stop there and display a message" Scan ending due to error condition see details nature of problem and possible recommended action' so when I click the details button, it shows "X-Ray signal level Hi/Lo did not match the filter drum position. Locus C Arm stat machine error in task o, index 278." I have checked the drum position which in position as recommended. Kindly help in this regard.