USA Negative Current Liabilities

[MSFC]

Hi all - I recently took over the books for my organization and have been cleaning up some sloppy bookkeeping/use of QBs. One of the things I am having trouble with is understanding why on our balance sheet several of our current liabilities are showing negative balances. For example, the accounts payable balance for the previous month is negative. When I pull a quick report of all transactions for the year everything balances out (meaning that I see both the bill and Bill payment check) except for several entries where the bill was recorded in December 2013 but not paid until early January 2014 (Bill is dated December 2013, bill payment check is dated January 2014). Could this be the cause of a negative balance? Thanks in advance for any thoughts.