[web2py] Problem with SQLFORM.grid

[brushek]

Hello,

I have following table with custom type (database: postgres):
from gluon.sql import SQLCustomType
inet = SQLCustomType ( type='string', native='inet', encoder=lambda x:
repr(str(x)))
db.define_table("serwery",
        Field("id_klienci",db.klienci),
        Field("ip_serwera",type=inet,requires = IS_IPV4()))

When I try to use SQLFORM.grid, like this:

@auth.requires_login()
def dodajserwer():
    response.flash = T('Serwery')
    form=SQLFORM.grid(db.serwery)

    if form.accepts(request.vars, session):
        response.flash='Serwer dodany'
    elif form.errors:
        response.flash = 'popraw'

    return dict(form=form)

I get following error:
Traceback (most recent call last):
  File "/home/users/brushek/web2py/gluon/restricted.py", line 194, in
restricted
    exec ccode in environment
  File "/home/users/brushek/web2py/applications/welcome/controllers/
default.py", line 138, in <module>
  File "/home/users/brushek/web2py/gluon/globals.py", line 145, in
<lambda>
    self._caller = lambda f: f()
  File "/home/users/brushek/web2py/gluon/tools.py", line 2510, in f
    return action(*a, **b)
  File "/home/users/brushek/web2py/applications/welcome/controllers/
default.py", line 60, in dodajserwer
    form=SQLFORM.grid(db.serwery)
  File "/home/users/brushek/web2py/gluon/sqlhtml.py", line 1430, in
grid
    T = current.T
TypeError: reduce() of empty sequence with no initial value

Where can be problem ?

regards
brushek