Index was out of range. Must be non-negative and less than the size of the collection Error

[Pat]

I have a 3 Datagrids.
The dtgMaster is the main datagrid and after selecting a ROW i populate the
second datagrid dtgDetails and the same for
the 3rd datagrid dtgChild.
But the thing is after clicking on a ROW on the dtgMaster and then select a
ROW in the second datagrid and the go back to the
dtgMaster which is the main datagrid and try to PAGE i get the error

"Index was out of range. Must be non-negative and less than the size of the
collection. Parameter name: index"

At the line
Dim strFilter As String =
CStr(dtgDetails .DataKeys(dtgDe tails.SelectedI ndex)).Replace( "'", "''")
of the second DataGrid

Any ideas

Sub BindMaster()
Dim strQuery As String = "Select OrderID,Invoice Date,OrderDate From
CMRC_Orders ORDER BY " & viewstate("sort Field").ToStrin g & " " &
viewstate("sort Direction").ToS tring

'Dim objConn As SqlConnection = New
SqlConnection(C onfigurationSet tings.AppSettin gs("ConnectionS tring"))

Dim dataAdapter As New SqlDataAdapter( strQuery, objConn)
Dim ds As New DataSet

dataAdapter.Fil l(ds)
dtgMaster.DataS ource = ds
'dtgMaster.Curr entPageIndex = 0
dtgMaster.DataB ind()

End Sub

Sub BindDetails()
' getting the filter value from the master Grid's DataKeys
collection

If dtgMaster.Selec tedIndex <> -1 Then

Dim strFilter As String =
CStr(dtgMaster. DataKeys(dtgMas ter.SelectedInd ex)).Replace("' ", "''")
Dim strQuery As String = "Select t1.OrderDetailI D, t1.OrderID,
where t1.OrderID = '" & strFilter & "'"
Dim dataAdapter As New SqlCommand(strQ uery, objConn)

objConn.Open()
dtgDetails.Data Source = dataAdapter.Exe cuteReader()

End If
dtgDetails.Data Bind()

End Sub


Sub BindChild()
If dtgDetails.Sele ctedIndex <> -1 Then
'Dim objConn As SqlConnection = New
SqlConnection(C onfigurationSet tings.AppSettin gs("ConnectionS tring"))

'Error here
Dim strFilter As String =
CStr(dtgDetails .DataKeys(dtgDe tails.SelectedI ndex)).Replace( "'", "''")

'Dim strQuery As String = "Select t3.Feature from Orders where
t1.OrderDetailI D= '" & strFilter & "'"

Dim dataAdapter As New SqlCommand(strQ uery, objConn)
objConn.Open()

dtgChild.DataSo urce =
dataAdapter.Exe cuteReader(Comm andBehavior.Clo seConnection)

'Response.Write ("<b>" & strFilter & "</b>")

End If
dtgChild.DataBi nd()
End Sub