I can flash TWRP but not stock firmware?

[shotgun10ga]

I can successfully flash Twrp, And I have flashed a rom to use my phone, But i cant flash stock firmware? I just get "Nand write start" and then "FAIL" in ODIN. Any ideas if a pit file would be useful? My device is as followed: Galaxy S6 32 GB TELUS SM-G920W8.

Please reply if you have any ideas? Thanks, I have also tried kies and smart switch, I got nothing. Thanks

 

[shotgun10ga]

I can successfully flash Twrp, And I have flashed a rom to use my phone, But i cant flash stock firmware? I just get "Nand write start" and then "FAIL" in ODIN. Any ideas if a pit file would be useful? My device is as followed: Galaxy S6 32 GB TELUS SM-G920W8.

Please reply if you have any ideas? Thanks, I have also tried kies and smart switch, I got nothing. Thanks

Could this be because i flahed a 5.1.1 rom?