insert null into date fields

[holly]

Hi I need help with the below code as no matter wot I try it keeps inserting
the default #01/01/1900#

  If Len(QuoteReq_char) = 0 Then
          SQL = SQL & ", '" & Null & "'"
   Else
        SQL = SQL & ", CONVERT(datetime,'" & Format(QuoteReq_char, "dd mmmm yyyy") & "', 103)"
    End If
    SQL = SQL & "," & TargetPrem_money
    SQL = SQL & ",'" & MakeStrSQLAcceptable(TargetInsurer_char) & "'"
    If Len(ToCarrier_char) = 0 Then
         SQL = SQL & ", '" & Null & "'"
    Else
        SQL = SQL & ", CONVERT(datetime,'" & Format(ToCarrier_char, "dd mmmm yyyy") & "', 103)"
    End If

thanks

the code is set in an insert stmt to sql server 2000...I have not posted the
whol routine as its big but if need to I will