its a bit sciency, but you might find this website useful...
http://www.mynchen.demon.co.uk/Ketog...genic_diet.htm
In terms of veggies I am not sure which ones are on those lists, but I stick mostly to the following for the bulk of my veg and it works for me (though I have to admit to a bit of cheating with red peppers and onions - doesn't seem to affect my ketosis if I don't go overboard)
Celery
Asparagus
Courgettes (Zucchini)
Aubergine
all types lettuce leaves
Cabbage (green)
Spinach
Green Peppers
you do have to make sure that you get the balance of fat right...my diet includes around 2 dessert spoons of a good oil like rapeseed or olive...
But if it's not working and you are using the proscribed sachets, are there other hidden carbs somehwhere that you aren't accounting fo maybe, like milk or fruit?