If at any time following the Closing Date, the amount of an item listed or prorated in Section 11 shall prove to be incorrect (whether as a result of an error in calculation or lack of complete and accurate information as of the Closing), the party in whose favor the error was made shall promptly pay to the other party the sum necessary to correct such error upon receipt of reasonable proof of such error, provided that notice of such error. The provisions of this Section 11.1.3 shall survive the Closing indefinitely and not be merged therein. All prorations shall be made based on the number of calendar days in such year or month, as the case may be.