Problem with EM_....

[BestCoder]

Could someone please test this code or tell me what's wrong with it? It uses a single form with a richtextbox named rtfScripts. I am trying to get it to resize according to the number of lines in it... but I can't even get the lineindex to return anything but -1.

Private Const LF_FACESIZE = 32
Private Const LF_FULLFACESIZE = 64
 
Private Const WM_GETFONT = &H31
Private Const WM_USER = &H400
Private Const EM_GETLINECOUNT = &HBA
Private Const EM_GETLINE = &HC4
Private Const EM_LINELENGTH = &HC1
Private Const EM_LINEINDEX = &HBB
Private Const EM_GETRECT = &HB2
Private Const EM_GETCHARFORMAT = (WM_USER + 58)
 
Private Const SCF_SELECTION = &H1
 
Private Type CHARFORMAT
    cbSize As Long
    dwMask As Long
    dwEffects As Long
    yHeight As Long
    yOffset As Long
    crTextColor As Long
    bCharSet As Byte
    bPitchAndFamily As Byte
    szFaceName(LF_FACESIZE) As String
End Type
 
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, wParam As Any, LParam As Any) As Long
 
Private Sub Form_Load()
    Dim nLine As Long
    Dim nIndex As Long
    Dim nCurrentPos As Long
    Dim nTextsize As Long
    Dim cf As CHARFORMAT
    Dim nLineCount As Long
    
    rtfScripts.Text = "This is a test... This is a test... This is a test... This is a test... This is a test... This is a test... This is a test... This is a test..."
    
    nLineCount = SendMessage(rtfScripts.hwnd, EM_GETLINECOUNT, ByVal 0&, ByVal 0&)
    
    For nLine = 0 To (nLineCount - 1) Step 1
        
        rtfScripts.SelStart = nCurrentPos
        nIndex = SendMessage(rtfScripts.hwnd, EM_LINEINDEX, nLine, ByVal 0&)
        nCurrentPos = nCurrentPos + SendMessage(rtfScripts.hwnd, EM_LINELENGTH, nIndex, ByVal 0&)
        rtfScripts.SelLength = nCurrentPos
        
        SendMessage rtfScripts.hwnd, EM_GETCHARFORMAT, SCF_SELECTION, cf
        
        nTextsize = nTextsize + cf.yHeight
        
    Next nLine
    
    rtfScripts.Height = nTextsize + 10
End Sub