Each case must be reviewed on its own merits. The applications were likely under review by different officers. It may be time to engage an attorney. An attorney could appear at an infopass appointment on your behalf to attempt to ascertain the reason for the delay. An attorney can also to legal action against USCIS if necessary. You can read more about deriving citizenship at http://myattorneyusa.com/citizenship-and-naturalization.
Answered on Feb 25th, 2016 at 3:45 PM