htc 510 desire sprint failed in fastboot flash boot b.img

hello guys i have got a htcopcv1 510 lock with sprint i have sucess unlock
its bootloader
***unlocked******
A11_CHL PVT SHIP S-ON
HBOOT-3.19.0.0000
RADIO-1.46.40.0721
OPENDSP-V28.2.2.00546.0331
OS-1.47.652.1
EMMC-BOOT 1024MB
DEC 6 2014 00:54:25.0

i have getting following error in this cammand

i have follow this website to unlock error in step 3

[Tutorial] How to unlock HTC Desire 510 Sprint/Virgin/Boost – Tutorial and Guides – Reliance Mobile (CDMA & GSM) – Discussion Forums

plz help to solve this problem :confused::confused::confused: