关于per的问题，请帮忙分析

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Software version   : v2.0.3 (30 days trial version)
IP Address         : 192.168.100.254
Interface type     : TCPIP
Interface Port     :
Log all            : Enabled - no signal file
Log fail           : Enabled - no signal file
IQ Flow File       : IQ_Flow_TEST.txt
IQ DUT File        : IQ_DUT_Chipset.txt
MAC Assign Method  : Read from barcode reader, pass only
Serial no. Method  : Use date and time
Failure Handling   : Stop
Product ID         : RTL8196C
Station ID         : 0011
______________________________________________________________________________
Current time : Mon Nov 21 10:26:07 2011
Illegal command in flow file : 'IQ_RX_VERIFY_START '
Illegal command in flow file : 'IQ_RX_VERIFY_END'
Illegal command in flow file : '        IQ_CAL_TX_OUTPUT        '
Illegal command in flow file : 'WRITE_EEPROM_START'
Illegal command in flow file : 'WRITE_EEPROM_END'
Illegal command in flow file : 'IQ_TX_VERIFY_START '
Illegal command in flow file : 'IQ_TX_VERIFY_END'
Illegal command in flow file : 'WRITE_EEPROM_START'
Illegal command in flow file : 'WRITE_EEPROM_END'
illegal command 'IQ_FIXED_ATTEN_2_4_CHAIN3' at attenuation setup file！
illegal command 'IQ_FIXED_ATTEN_5_CHAIN3' at attenuation setup file！
IQ Tester Initialize
IQ API Version:
        IQmeasure: 1.7.13.0 (2009-10-14)
        iqapi: 1.7.48 (Dec 9 2009)
        iqapitc: 1.2.39 Dec 2 2009
        iq_nxn: 1.1.7a (2009-11-20)
        IQV_mw: 3.2.5g Jul 24 2009 Tester 1
        SN: IQF09663
        iq_nxn_signal: 1.1.15 (2009-09-24)
        iq_max_signal: 1.0.46 (2008-08-26)
        iq_zigbee_signal: 1.0.8 (2009-10-20)
        iq_nfc_signal: 0.2.19 (2009-09-11)
        bluetooth: 1.1.2.h December 8 2009
        iqv_analysis: 1.4.1.b Sept 24 2009
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Current time : Mon Nov 21 10:26:20 2011
Serial no.   : 111121-102620

1 . IQ_INITIALIZE_TESTER EC:T0109 ____________________________________________
    Test Time = 0.015 sec
2 . IQ_OBTAIN_CONTROL EC:T0109 _______________________________________________
    Test Time = 1.860 sec
3 . IQ_INSERT_DUT EC:T0191 ___________________________________________________
    Test Time = 0.000 sec
4 . IQ_INITIALIZE_DUT EC:T0191 _______________________________________________
tftp -i 192.168.10.1 put nfjrom
>> Timeout occurred
API: OpenDUT
API: StartTest
    RF Type: 2T2R
    Test Time = 20.547 sec
5 . IQ_VERIFY_RX_PER 2442 11M ANT1 EC:T0040 __________________________________
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:500
    Num_Packet_Err:0
API: StopRxPacket
    PER @ -82dBm : 0.00%                   (   0.00 *.................   8.00)
    Test Time = 1.562 sec
6 . IQ_VERIFY_RX_PER 2442 11M ANT2 EC:T0040 __________________________________
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:416
    Num_Packet_Err:84
API: StopRxPacket
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:432
    Num_Packet_Err:68
API: StopRxPacket
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:416
    Num_Packet_Err:84
API: StopRxPacket
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:408
    Num_Packet_Err:92
API: StopRxPacket
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:418
    Num_Packet_Err:82
API: StopRxPacket
API: StartRxPacket
    Num_Frames:500
    Num_Packet_OK:401
    Num_Packet_Err:99
API: StopRxPacket
    PER @ -82dBm : 19.80%                  (   0.00 .................X   8.00)
    Test Time = 4.844 sec
**************************************************************
          Test aborted by 'STOP ON FAIL' setting！
**************************************************************
50. IQ_RELEASE_CONTROL EC:T0109 ______________________________________________
    Test Time = 0.125 sec
51. IQ_REMOVE_DUT EC:T0191 ___________________________________________________
    CloseDutConnection
API: StopTest
API: CloseDUT
    Test Time = 1.437 sec

----------------------------------------------------------------------------
                             Test Time Summary
                             =================
1 . IQ_INITIALIZE_TESTER EC:T0109                              :   0.01 sec
2 . IQ_OBTAIN_CONTROL EC:T0109                                 :   1.86 sec
3 . IQ_INSERT_DUT EC:T0191                                     :   0.00 sec
4 . IQ_INITIALIZE_DUT EC:T0191                                 :  20.55 sec
5 . IQ_VERIFY_RX_PER 2442 11M ANT1 EC:T0040              0.00  :   1.56 sec
6 . IQ_VERIFY_RX_PER 2442 11M ANT2 EC:T0040             19.80  :   4.84 sec
----------------------------------------------------------------------------
Total Test Time       : 28.52 sec
IQ Tester Usage Time  : 28.52 sec
----------------------------------------------------------------------------
                          *****************
                          **** F A I L ****
                          *****************
Please remove DUT, press any key to continue OR 'X' key to exit........
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当把RF部分铁盖盖上时，测试结果如上，拆下时测试pass，为什么啊?