Charts Do Not Automatically Update When Data Changes

Hopefully this is an easy one. I have a series of charts in MS Excel that point to data on the same worksheet. The data on the worksheet is calculated using a VBA function. When the data is updated by the VBA function the new numbers are not reflected in the charts that are pointing to them. I tried calling Application.Calculate, but that didn't do the trick. Any thoughts?

UDPATE:

I was able to duplicate this issue on a much smaller scale. Here's how:

• Create a new workbook
• Rename Sheet 1 to "Summary"
• Rename Sheet 2 to "Data"

• Open the Summary sheet in the VBA editor and paste the following code:

  Private Sub Worksheet_Change(ByVal Target As Range)
     If Target.Parent.Range("worksheetDate") = Target Then
        Application.CalculateFull
     End If
  End Sub
  

• Create a new VBA module

• Paste the following code into the new VBA module (I apologize - I can't get Stack Overflow to format this correctly for the life of me - this is the best I could get it to do):
  .

   Function getWeekValue (weekNumber As Integer, valuesRange As Range) As Integer   
  
   Dim aCell As Range  
   Dim currentDate As Date  
   Dim arrayIndex As Integer  
   Dim weekValues(1 To 6) As Integer  
  
   currentDate = ThisWorkbook.Names("worksheetDate").RefersToRange.Value
   arrayIndex = 1  
   For Each aCell In valuesRange 
       If month(currentDate) = month(ThisWorkbook.Sheets("Data").Cells( _  
                                     aCell.Row - 1, aCell.Column)) Then
           weekValues(arrayIndex) = aCell.Value 
           arrayIndex = arrayIndex + 1 
       End If 
   Next
  
   getWeekValue = weekValues(weekNumber)   
   End Function  
  

  .

• Modify the Data worksheet to match the following image:

• Select Cell B1 and name the range "work