That's normal. In fact you never was having 4.2.6 in the device, you've never shsh for any 4.2.6 as the device came with another version higher than the one you wishing to have on your device. At this point, you will not be able to downgrade, itunes will not allow any downgrade on any of his iDevices. What iDevice are you using? If you are having an iPhone4 what about the latest firmaware? You don't like it? It's stable and depending on your baseband it's unlockable as well.
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