find the highest value in a column and in a textbox

Hi.
I need to have the highest value of a column in my TextBox, then add 1.

if anyone can help me

Private Sub UserForm_Initialize()
    Dim RowNo As Long, rngMax As Range
    Set rngMax = Worksheets("Sheet1").Range("A2:A10000")
    On Error Resume Next
    With Application.WorksheetFunction
        RowNo = Selection.Find(What:=.Max(rngMax), LookIn:=xlValues, LookAt:= _
        xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:=False).Row
    End With
    If RowNo > 0 Then Me.TextBox5 = RowNo + 1
    On Error GoTo 0
End Sub