I know my syntax is incorrect just need to know if there is a simple way to do this. What I thought might work obviously didn't

Any suggestions would be greatly appreciated.

What I tried:
===================================
<%
IF NOT isempty(Request.Form("next")) then

if request.form("storeid") = "999" then
MsgBox "Incorrect Selection"
response.redirect "./default.asp"
else
response.redirect "./clientadd.asp"
end if

end if
%>
===================================


Kind Regards,
Hakan