Windows 7 with bootcamp doesn't recognize my 64-bit

I have install Windows 7 32-bit on my iMac couple of months ago. Yesterday i tried to upgrade it to 64-bit( what i mean by upgrade is that i wiped all my windows partition from the iMac side and the started the installation), but when i was done doing all the bootcamp stuff and my computer booted with windows, it says i still run a 32-bit version of windows 7. I'm sure it was a 64-bit version and i have no clue what could be the problemm