data table questions

I have a array of datarows that sometimes has length and sometimes has 0 lenght.  Do you see anything in this code segment that would make this aarray get set to 0.  Whats strange is it works sometimes and sometimes it doesnt.

Private Sub Focus(ByVal field As String, ByVal criteria As String)
                Dim expression As String
                Dim criterias As String()
                If InStr(field, "Date") Then
                    criterias = criteria.Split(",")
                    expression = field & " >= #" & criterias(0) & "#" & " AND " & field & " <= #" & criterias(1) & "#"
                Else
                    expression = field & " IN (" & criteria & ")"
                End If
                Dim adrEdit() As DataRow = dt.Select(expression)
                If UBound(adrEdit, 1) > -1 Then
                    Dim cdt As New DataTable
                    cdt = dt.Clone
                    For Each dr As DataRow In adrEdit
                        Dim cdr As DataRow
                        cdr = cdt.NewRow
                        For i As Int16 = 0 To dt.Columns.Count - 1
                            cdr(i) = dr(i)
                        Next
                        cdt.Rows.Add(cdr)
                    Next
                    dt = cdt.Copy
                Else
                    dt.Clear()
                End If
            End Sub