Everything was set correctly.

When I use "GET">
> form page
...
<form method="get" ...>
...

> script page
...
rs.AddNew
'call metpost
call metget
rs.Update
...

########################

When I use "POST">
> form page
...
<form method="post" ...>
...

> script page
...
rs.AddNew
call metpost
'call metget
rs.Update
...
#############

I fixed it this way, and now it works:
> script page

Sub metpost
for each key in Request.Form
if key <>"Submit" then
rs(key) = Request.Form(key)
end if
next
End sub

I don't know why the EXECUTE command didn't work, but what's important is that now I can do what I want.
Thanks guys.