Excel VBA .Replace happens on specified sheet and others

[Tanquen]

This VBA code is working but sometimes the Find and Replace happens on the specified sheet "CSV" and other "Function" sheet with the same cell content. I'm guessing it because the "Function" sheet also has the range of cells with values to then find in the "CSV" sheet. But the .Replace function calls out the "CSV" sheet. ???

Sub Button3_Click()
    '***Find & Replace - Link to Function Sheet Cells
        Dim sh As Worksheet, rng As Range, SFind As String, SReplace As String, fRng As Range, CL As Range
                    
        Set sh = Worksheets("CSV")
    
        With sh
            Set fRng = Worksheets("Function").Range("A10:A1000")
            
            Worksheets("Function").Range("B10:C1000").Replace What:="-", Replacement:="_"
            
            For Each CL In fRng
                'If Not CL Is Nothing Then
                If Not IsEmpty(CL.Value) Then
                    SFind = CL.Value
                    SReplace = "=Function!" & CL.Offset(, 1).Address
                    If Not IsEmpty(CL.Offset(, 1)) Then
                        Worksheets("CSV").Range("A1:D1000").Replace What:=SFind, Replacement:=SReplace, LookAt:=xlWhole
                    End If
                End If
            Next CL
        End With
End Sub