hvad mener den med Invalid use of Null: 'Split'

jeg får følgende fejl

Microsoft VBScript runtime error '800a005e'

Invalid use of Null: 'Split'


min kode ser ud som følger:

<%

Set Conn = Server.CreateObject("ADODB.Connection")
DSN = "DRIVER={Microsoft Access Driver (*.mdb)}; "
DSN = DSN & "DBQ=" & Server.MapPath("/../db/test.mdb")
Conn.Open DSN
strSQL = "Select * From FORUM_MEMBERS ORDER by MEMBER_ID"
Set rs = Conn.Execute(strSQL)

Do
    arrBillede = Split(rs("M_AVATAR_URL"),".")
    Conn.Execute("UPDATE FORUM_MEMBERS SET M_AVATAR_URL = '"& arrBillede(0) & ".jpg" &"' WHERE MEMBER_ID = " & rs("MEMBER_ID"))
rs.movenext
Loop until rs.eof
%>