Problem generating from model

Hello everyone;

I'm quite new to madgraph and event generation. I was asked to generate the following process from the model RS_bulk_ktilda:
proton proton collision creating a gravition (y, pdg_id = 39) which decays in two Higgs each of them decaying w+ w-. Now 3 ws decay hadronically and one creates a lepton neutrino pair. This process as written gives errors but if i impose one H to decay into a b b~ pair or a photon pair everything is fine. I'll post here the proc card that i use to generate the 1st event that doesn't work with its error. Am i missing something here or am i doing something wrong? Thanks everyone.

import model RS_bulk_ktilda
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
define q = u c d s b u~ c~ d~ s~ b~
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
define lep = e+ e- mu+ mu-
define nus = ve~ vm~ ve vm
define ws = w+ w-
define vs = ws z
define vis = lep q
generate p p > y, (y > H H, (H > w+ w-, w+ > q q, w- > lep nus), (H > w+ w-, w+ > q q, w- > q q ) ) @1
add process p p > y, (y > H H, (H > w+ w-, w- > q q, w+ > lep nus), (H > w+ w-, w+ > q q, w- > q q ) ) @2
output Bulk_signal
launch

The error here is:
.
.
.
Survey return zero cross section.
   Typical reasons are the following:
   1) A massive s-channel particle has a width set to zero.
   2) The pdf are zero for at least one of the initial state particles
      or you are using maxjetflavor=4 for initial state b:s.
   3) The cuts are too strong.
   Please check/correct your param_card and/or your run_card.
Zero result detected: See https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/FAQ-General-14

note that the following processes work fine:

generate p p > y, (y > H H, H > q q, (H > w+ w-, w+ > q q, w- > lep nus) ) @1
add process p p > y, (y > H H, H > q q, (H > w+ w-, w- > q q, w+ > lep nus) ) @2

generate p p > y, (y > H H, H > a a, (H > w+ w-, w+ > q q, w- > lep nus) ) @1
add process p p > y, (y > H H, H > a a, (H > w+ w-, w- > q q, w+ > lep nus) ) @2

And this does not work either:

generate p p > y, (y > H H, H > z z, (H > w+ w-, w+ > q q, w- > lep nus) ) @1
add process p p > y, (y > H H, H > z z, (H > w+ w-, w- > q q, w+ > lep nus) ) @2

generate p p > y, (y > H H, H > w+ w-, (H > w+ w-, w+ > q q, w- > lep nus) ) @1
add process p p > y, (y > H H, H > w+ w-, (H > w+ w-, w- > q q, w+ > lep nus) ) @2

This doesn't work too but the error this time is different:

generate p p > y, (y > H H, H > w+ w-, H > w+ w-) @1
.
.
.
Zero result detected: No Phase Space. Please check particle masses.

INFO:
quit
INFO:
Generation failed (no results.dat file found)

Let me know if you need more information about the model or so on, i'll provide them. Thanks again for your kind attention. have a nice day.

Giacomo