Can't close a Purchase Order

We had a purchase order did not automatically close.  When the user looked at it, the second line that had been cancelled had a status of open.  When the user went through the process to perform a "final close" and it appeared to work.  When the user re-queried the P.O.  The second cancelled line still showed with a status of open.  Nothing was ever received or partially received against this line.  I believe this line was cancelled at the line level.  How do we get this cancelled line to close?