Creating a global variable to copy a datatable from one function doesn't show the data on another function call. Not sure why!

(GridView1.Rows(i).Cells(x).Text.ToString

Public Class GlobalVariable
    Public Shared Dttbl As New DataTable
End Class

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not Page.IsPostBack Then
        Call loadExcel()
        Call callGlobalVariable()
    End If
End Sub

 Public Function loadExcel()
Dim MyConnection As System.Data.OleDb.OleDbConnection
Dim MyCommand As System.Data.OleDb.OleDbDataAdapter
Dim taskTable As New DataTable

Dim filePath = Path.Combine(GlobalVariable.savedPath, GlobalVariable.excelFileName)

'Code to Use an Oledb Connection to get data from the Excel File
If File.Exists(filePath) Then
    MyConnection = New System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & filePath & ";Extended Properties='Excel 12.0 Xml;HDR=YES;';")
    MyCommand = New System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection)
    MyCommand.Fill(taskTable)
    'Persist the table in the Session object.
    'Below is what i am doing to copy the task table globally so i can use it in a function call. HOWEVER IT DOESN't Show in another function call. not sure why. 
    GlobalVariable.Dttbl = taskTable.Copy
    Session("TaskTable") = taskTable

    'Bind data to the GridView control.
    BindData()
    MyConnection.Close()
Return Nothing
End Function

Public Function callGlobalVariable()
'The below shows up empty i am not sure why. But it is able to read above in the loadExcel() function. 
GlobalVariable.Dttbl.Rows(0).ItemArray(0).ToString()
Return Nothing
End Function