EPCS .pof .sof the different phenomenon

I want to upload 0--65535 from FPGA to PC. The 0 is the first number and the 65535 is the last one. When I download the .sof to the FPGA ,the result is right ;but When I start the FPGA from the EPCS ,the result is wrong, the first number is not zero.What can I do to make the first number is 0. Thank you !!