fejl med mid

Hej!

Jeg får denne fejl:
Microsoft VBScript runtime error '800a0005'

Invalid procedure call or argument: 'mid'

/aktivekode.asp, line 9


Her er koden:
<%
function MakeCode(count)
Dim randchars
randchars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ012345678901234567890123456789"
Dim s
s = ""
Randomize
For I = 0 To Count-1
s = s + mid(randchars, Int(Rnd * (Len(randchars)-1)), 1)
Next
MakeCode = s

end function

Dim aktiveringskode
aktiveringskode = MakeCode(30)
%>
<%=aktiveringskode%>

/Peppino