Problem with "cannot read update.bin" in 4.6.4 to 4.6.3 downgrade

I have 4.6.4 AT&T OS and I want to downgrade to 4.6.3 unlock OS. In recovery mode the phone is connected with computer, I see serial number and "sideload" next, the update.bin file is in ADB folder, but at next step I get the message
"cannot read update.bin" . I run Win 10 on computer, I try also on Win 7, same problem. I downloaded
4.6.3 unlock OS first with Microsoft Edge, it has .zip extension, then downloaded with Chrome it came with .bin extension, neither one work. Any ideas ? Because I run out.