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The reason you are getting that message is that your iPad is not in recovery mode yet. You have to put it to recovery mode, then only you will be able to restore it.
Follow the steps below to restore your iPad by putting it to recovery mode.
First download and install latest iTunes on your computer from here (ignore if you already did this step) : https://www.apple.com/itunes/download/
Then connect the iPad to your computer with the USB Cable.
Open iTunes application on your computer.
Very improtant step : On your iPad press and hold the Home button and the Power button at the same time for 10-15 seconds or until your iTunes shows a message telling you that it has detected an iPad in recovery mode.
Click Restore or Restore and Update button.
Note : Put it to recovery mode while connected to computer and also in recovery mode your iPad will show USB cable pointing to iTunes logo. And it will take a while to restore it.
Please let me know if that didn't work, so I will continue to help you until we fix the problem.
Remember, this is not my final answer. If my solutions didn't work please don't rate me bad or poor. Instead please reply back to me and I will continue to help you until we fix the problem or you are satisfied.