Need to Convert Formula R1C1 into A1-style but the Formula String exceeds 255 characters

Hi - I have run into a problem where I am converting a formula in R1C1 format to A1-style. I am using a formula conversion function that works fine as long as the length of the original formula string is less than 256 characters.
For example,
Original formula: "=R4C5*R7C5+R4C6*R7C6+R4C6*R7C7...." (Formula Length < 256)
Converted formula "=$E$4*$E$7+$F$4*$F$7+$G$4*$G$7...." (Formula conversion works fine)

But when the code gets to Row 10 and above, the formula string length exceeds 256 characters and the resulting value in my cell is "#Value". Here is a module of code where I have replaced most of the For-Next variable counters with constants. Is there a better way to generate the formula where I do not have to convert from R1C1-style to A1-style?

Sub CreateFormula()

    Dim i, j As Integer
    Dim RN As Integer ' Row Number ID
    Dim CN As Integer ' Col Number ID
    Dim WFR, WFC As Integer  'Weighting Factor Row and Weighting Factor Column ID
    Dim MyFormula, NewFormula As Variant
'Add Formulas
    Range("AD7").Select
    RN = 7 'starting row number
    CN = 5 'Starting col number
    
    WFR = 4  'weighting factor row
    WFC = 5  'weighting factor column
    Dim BP_Formula_Str As String
    
    For j = 1 To 15  'row counter
        
        BP_Formula_Str = "=R" & WFR & "C" & CN & "*R" & RN & "C" & CN
        
        
            For i = 1 To 20  'column counter
            
                CN = CN + 1
                BP_Formula_Str = BP_Formula_Str + "+R" & WFR & "C" & CN & "*R" & RN & "C" & CN
               
            
            Next i
        
        'Convert Formula
           MyFormula = BP_Formula_Str
           Call FormulaConvert(MyFormula, NewFormula)
           'Debug.Print Len(MyFormula) & " - " & Len(NewFormula)
              
        'Paste Formula
            ActiveCell.formula = NewFormula             'now in A1-style formula
            ActiveCell.Font.Size = 9
            ActiveCell.Font.Bold = True
            
        'Reset Variables
            BP_Formula_Str = ""
            ActiveCell.Offset(1, 0).Select
            CN = WFC
            RN = RN + 1
    Next j
    
   'Format column width
        With Selection
        .EntireColumn.AutoFit
        End With
End Sub

Function FormulaConvert(MyFormula As Variant, NewFormula As Variant)
    Dim inputFormula As Variant
    inputFormula = ""
    inputFormula = MyFormula   'original formula in R1C1 format
    
    'NewFormula contains the A1-style version
    Debug.Print Len(inputFormula)
        
        NewFormula = Application.ConvertFormula( _
        formula:=inputFormula, _
        fromReferenceStyle:=xlR1C1, _
        toReferenceStyle:=xlA1, ToAbsolute:=xlAbsRowRelColumn)
    
    'Debug.Print Len(NewFormula)
    
End Function

Hi JakobShavn,
Thanks for your suggestion. I will look up the SUMPRODUCT() formula and see if this will be an alternate way to generate this long formula. - VBA_Gary

A fix has been found.
The problem was that I started using the R1C1-style format rather than A1-style format for building my formula. The easier way to do it was to use the ADDRESS object as shown below. Since my formula used both relative and absolute addressing, the Evaluate(ADDRESS) method allowed me to create the formula using the 4 different options.

Thanks to those that added their comments.

    Dim RN As Integer ' Row Number ID
    Dim CN As Integer ' Col Number ID
    Dim WFR, WFC As Integer  'Weighting Factor Row and Weighting Factor Column ID
    Dim Formula_Pt1, Formula_Pt2 As String  'Two parts to the formula
    Dim Ce1, Ce2, Ce3, Ce4 As Variant  'Ce1 means Cell 1, Ce2 means Cell 2 , etc.
    
    
    ActiveCell.Offset(1, 0).Select
    RN = ActiveCell.Row      'Get the row number for the current active cell
    CN = Range("E:E").Column 'Get the column number for column E
    
    WFR = 4      'Weighting Factor Row is 4
    WFC = 5      'Weighting Factor Col is 5 ("E")

    Dim BP_Formula_Str As String

        'sample "E$4"  AbsoluteRowRelativeColumn addressing, option 2
           Ce1 = Evaluate("Address(" & WFR & "," & CN & ", 2, 1)")
        'sample "E7"   Relative addressing, option 4
           Ce2 = Evaluate("Address(" & RN & "," & CN & ", 4, 1)")  

        
        Formula_Pt1 = Ce1 & "*" & Ce2        ' Sample "E$4*E7"
        BP_Formula_Str = "=" & Formula_Pt1
        
        For i = 1 To 21
        
            CN = CN + 1

            'AbsoluteRowRelativeColumn, option 2
            Ce3 = Evaluate("Address(" & WFR & "," & CN & ", 2, 1)")             
            Ce4 = Evaluate("Address(" & RN & "," & CN & ", 4, 1)")  'Relative, option 4
            
            Formula_Pt2 = Ce3 & "*" & Ce4    
            BP_Formula_Str = BP_Formula_Str & "+" & Formula_Pt2
        
        Next i

        'Paste Formula
        ActiveCell.formula = BP_Formula_Str    'now formula is in A1-style 
        ActiveCell.Font.Size = 9
        ActiveCell.Font.Bold = True
        
        'Reset Variables
        
        BP_Formula_Str = ""
        ActiveCell.Copy

        'Now paste the formula down the column
        Range(ActiveCell, ActiveCell.Offset(FilerCount - 1, 0)).PasteSpecial
          
    With Selection
      .EntireColumn.AutoFit
    End With

@ VBA_Gary

Based on your last post it seems that you solved your issue but you haven't marked your thread as SOLVED. I'll do that for you now but please keep in mind for your future threads that Rule #9 requires you to do that yourself. If your problem has not been solved you can use Thread Tools (located above your first post) and choose "Mark this thread as unsolved".
Thanks.

Thanks Cutter for marking this as SOLVED. I looked around the website for the way to mark it as solved but did not find it. I now see it under the Thread Tools tab. Thanks for your help. - VBA_Gary