Aussiedistiller, Home Distilling, Moonshine, Home Brew

Hi folks,
What have I done wrong.
I usually make my tpw as per the recipe for 25lt. I decided to upgrade to a 50lt mash, so naturally I just doubled all the ingredient sizes and now it's just sitting there doing nothing, if I stir it up it bubbles away for 30 seconds or so and then goes back to nothing. Any ideas.
Cheers.

Whats the temp of the mash?

Did it actually start?
If it did but has now stalled have you checked the Ph.

If temp, water, tomato paste, ph etc are all the same as you usually run, perhaps it could be the yeast letting you down. Was it the same brand of yeast? Could it be that the yeast is too old?

Bubbles aren’t a very accurate indicator of activity. What was the starting gravity, and what is it now?

Thanks for the replies, same brand of yeast, however I have had it in the pantry for a while, temp was 30C when I added the yeast. I have never taken the S.G of my mash, I just make it and wait for the bubbles to stop coming from the trap. It never started to do anything from the get go, and it's been three days now. Temp is in the mid to high twenties. I may try some fresh yeast tomorrow and see how it goes, and I'll make my usual 25lt mash and see what happens. Once again thanks to everybody that replied.
Cheers.