在ise iMPACT上载到板子下时出现以上异常

在ise iMPACT下载到板子上时出现以下错误
ERROR:iMPACT:1525 - File c:/xup/markets/plds/workshops/courses/v81_fpga_flow/xupv2pro/labsolutions/verilog/lab3/time_const/loopback.bit can not be found.
ERROR:iMPACT:2009 - Fail to add device by file c:/xup/markets/plds/workshops/courses/v81_fpga_flow/xupv2pro/labsolutions/verilog/lab3/time_const/loopback.bit.
ERROR:iMPACT:2587 - Failed to add device 2.
------解决方案--------------------------------------------------------
找不到.bit文件