Cell Value in excel it is not updating the referenced function cell

[ahmadjf93]

I have problem in this excel:
Excel Sheet for INT-2073.xlsx
I am trying to update cell B1 but C1 which contains function referencing to A1 and B2 it is not updating the value.
This is the code I am using

Dim FileName As String
Public OutputDoc As SpreadsheetDocument
Dim AltChunkCount As Long = 0
Dim MainPart As WorkbookPart
Dim MainPartSheets As Sheets
Dim MainPartSheetData As SheetData
Public Sheets As New ArrayList

FileName = OpenFileName
OutputDoc = SpreadsheetDocument.Open(FileName, True)
MainPart = OutputDoc.WorkbookPart
MainPartSheets = MainPart.Workbook.GetFirstChild(Of Sheets)()
AltChunkCount = 1

Dim ExcelWorkbook As Workbook = ExcelDocument.OutputDoc.WorkbookPart.Workbook
OutputDoc.WorkbookPart.Workbook.CalculationProperties.ForceFullCalculation = True
OutputDoc.WorkbookPart.Workbook.CalculationProperties.FullCalculationOnLoad = True

Dim CurrentCell As Cell = GetCell("sheet1", 1, "B")
    If CurrentCell IsNot Nothing Then
        CurrentCell.CellValue = New CellValue(Value)
        CurrentCell.DataType = CellValues.Number
    End If

MainPart.Workbook.Save()
OutputDoc.Close()