NAND and DDR ok, still stuck at "waiting for SFT on the omapl-138"

Dear Sir：

        We use sfh_OMAP-L138.exe  to earse  and burn  NAND  FLASH through com port， most board  can be earsed and burned.  few board stuck at ""waiting for SFT on the omapl-138" when earse,  I check NAND and DDR throuhg CCS , test result is OK.  I changed NAND and DDR  chip , it  still stuck at  ""waiting for SFT on the omapl-138" . I don't know how to slove it.

      Wish get your help,

Howard