Xperia Pro/Neo/V/L :: Unlocked Phone Does Not Work On Cell Carriers?

I bought a new, unlocked Xperia Ray from Hong Kong, China. I also upgraded it to the latest available software: 4.1.B.0.587.This Xperia Ray unlocked phone does not work on Bell, Rogers or Videotron carriers in Canada who own the three Canadian cell networks. The IEMI number is rejected from these carriers. I tried the Virgin SIM (uses the Bell network) and the Rogers (Rogers network) SIM, and neither one works. I also called Telus, and no go either.Bell has other users who use the Xperia Ray and one of their affiliates Fido sells the Xperia U and the Xpreia Go. These phones show the same network specs as the Ray (HSDPA 850 / 1900 / 2100 - ST18a).Bell network (Virgin and Fido): phone must be HSPA (or UMTS) and,850 MHz and 1900 MHz compatible. (They use HSPA+) ,Rogers network: HSPA+ 850/1900 MHz ,Videotron: HSPA 1700/2100 MHz

I called Bell customer service and they say that it must be a different phone from the Canadian Xperia Ray... but that does not make sense. Isn't there only one Xperia Ray version??? How can one Xperia Ray work and the other not work???Can anyone clearly explain the problem to me? I don't get it and it really sux cause now I need to return the phone, which I really like.