[web2py] form.accepts() with reference to other table

[Oskari]

Hi!

I'm having trouble making an insert with form.accepts()

Currently I have a custom auth_user that has one extra field:
Field('accountID', db.accounts) with
custom_auth_table.accountID.requires = IS_IN_DB(db,db.accounts.id,id)

While trying to modify variables it fails with "not found in db"

def func():
    form=SQLFORM(db.auth_user)
    request.vars.accountID = 1
    if form.accepts(request.vars,session):
        response.flash = "Succesfully created user"
    return dict(form=form)

Why does not form.accepts() recognize and accept my accountID?