formula using GETPIVOTDATA is not automatically recalculating

[obiron]

using Excel 2007

I have the following formula

=IF
  (ISERROR
    (GETPIVOTDATA
      ("Contact_ID",'BackSheet1 - TAM FFW'!$A$3,
       "Staff_Date",
       COLUMN(H24)-4,
       "Contact Type",
       "Tel",
       "Service/Error",
       $C22
      )
    ),
    0,
    GETPIVOTDATA
      ("Contact_ID",
       'BackSheet1 - TAM FFW'!$A$3,
       "Staff_Date",
       COLUMN(H24)-4,
       "Contact Type",
       "Tel",
       "Service/Error",
       $C22
      )
  )
 
+ 
 
IF
  (ISERROR
    (GETPIVOTDATA
     ("Contact_ID",
      'BackSheet2 - NKN FFW'!$A$3,
      "Staff_Date",
      COLUMN(H24)-4,
      "Contact Type",
      "Tel",
      "Service/Error",
      $C22
      )
    ),
    0,
    GETPIVOTDATA
      ("Contact_ID",
       'BackSheet2 - NKN FFW'!$A$3,
       "Staff_Date",
       COLUMN(H24)-4,
       "Contact Type",
       "Tel",
       "Service/Error",
       $C22
      )
  )

Basically checking to see if a pivot cell exists in each of two pivot tables and adding the values together. $C22 refers to a cell which has a string which appears as a row heading and COLUMN(H24)-4 refers to a month number. this is designed so that the formula can be copied around the worksheet and will still work (which is does...)

I had the second pivot table on a worksheet named 'BackSheet2 - NKW FFW' and so the second part was not finding anything. I renamed the worksheet to be the same as in the formula and hit F9 recalc but the cells did not recalculate. When I go into the formula and then back out again the cells recalculate correctly.

Is this a bug or am I doing something wrong?