Status 7 When Installing Custom ROMs

Hey guys, my name is Ryan, and I'm still fairly new to rooting. After rooting my S3 (AT&T version, i747) I installed a custom ROM, and later decided I didn't like it, but because I hadn't backed up the stock version using CWM (I'm using version 5.5.0.4, by the way) I decided to fully un-root the phone, and re-install the stock Jellybean OS using Odin. After rooting the phone again, everything seemed to work perfectly, CWM ran fine, and I could use root applications, but every time I tried to flash a custom ROM (even after wiping data/cache/dalvik cache) I got the following error.

Finding update package...
Opening update package...
Installing update...
assert failed: getprop("ro.product.device")=="d2att" || getprop("ro.build.product")=="d2att"
E:Error in /emmc/cm-10.0.0-d2att.zip
(Status 7)
Installation aborted.

This is happening with all ROMs, not just this one. I looked on all the other forums, but none seemed to help. Thank you so much for reading! Please help!