I'm having trouble debranding my sony ericsson w850i

I've found the firmware R1KG001_1250200_GENERIC_CY.bin
and R1KG001_FS_M_EAST_N_AFR_CY_RED_CID53.bin

(are these meant to have the extension .bin)



JDflasher gets to write file then it won't let me flash can anyone help?