I think you overwrote the unlocked firmware and locked the phone again when you flashed it with the generic firmware.. try using Remove SimLock Patch Generator to create an unlock patch for your firmware and then SEtool2Lite to upload the unlock patch to your phone. Make sure you apply the "quick access patch" to your phone before you apply your unlock patch though otherwise you will not be able to do it.
This tutorial will guide you through creating and applying the quick access patch.
Hope this helps ;)
..Jamie