This is a warning that the user has signed on to a year that has already been rolled forward for Year End processing.  It is only a warning. If this is the correct date, click OK and continue working.  

If this is an incorrect date, click Cancel and change the Business Date.

If you post to this previous year, you will want to perform the year end procedures again.  The year end tasks of Post Revenue & Expense and Roll Forward can be repeated as many times as is necessary.