Lacto fermentation troubles

[Adiecain]

I'm having a go at brewing some ginger beer (non alcoholic) for my daughter aged 6. Now I've had the starter brewing in my kitchen for a few days.... after three to four days it bubbles away like a good un... I add a little ginger and sugar every day and agitate regularly... But day five it goes belly up and stops fermenting... Clueless in Worcester here knows not why.... This has happened twice now.. Is it the colder temp in my kitchen at night that is stopping the action perhaps... Should I bung it in my airing cupboard? :cry:

 

[Adiecain]

ah well, it was worth a post

 

[Adiecain]

bunged it in the airing cupboard.. woke it up for one day then bugger all... stopped again....