Property tax Credit has been corrected Nebraska

After using Turbo tax I get the following message on my check from Nebraska.

"Your Property tax Credit has been corrected for one of the following reasons: 1) mathematical error was made in calculating the amount of credit: or 2) the amount of credit claimed exceeded the allowable amount. Refer to the Property tax Look-up Tool on the Department's website, revenue.nebraska.gov.  If you have additional questions please call the Department at (402)471-5729 or 800-742-7474"

According to Turbo tax, the Nebraska refund should be $1511  but I received $1423.  
Please advise if you found why the program did not do this right or what did I do wrong?