Try this way, select reboot into recovery from the rom manager app, then once there goto wipe cache and do that, then go to the advanced and under advanced select dalvik and wipe that. Then using the back button go back to the main screen and select install zip from sd card, then the next screen select install zip from sd card again, then scroll down to rom manager then select download and then select the gapps zip. Once the process is done it will put you back to the main menu and then just select reboot now n you should be good to go, it may seem complicated by my instructions but it is very easy. Good luck. Just whatever you do do not select wipe data, I have to go to bed now but good luck and I'm sure somebody else will help you out if you can't get it figured out in a little bit
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