Hi Henry -
The update file on your USB stick has to be coded to the serial number of your particular 700 unit. There are a few ways this could get mismatched: the update file on the USB stick was downloaded from an account not registered to your specific device; you changed to a different device since your account was created; or what probably happened is iFly's computer database in McKinney, TX burped.
A call to Ed or Steve at iFly should fix this in 60 seconds. I don't know if they will be open on Monday which is a holiday.
Good luck.
Steve (not "THE" Steve from iFly - another one)