HELP PICOLAX HASN'T WORKED!

[TitsalinaBumSqoosh]

DS (13) has an endoscopy tomorrow and was given 2 sachets of picolax to take at 9.30 and then again at 3.30.

After the 9.30 one he had a brief period of going to the loo a lot (maybe 20 mins?) but nothing since, the 3.30 one has done zilch.
He's had clear chicken broth and jelly and I'm worried it's not come out! Will it mean they can't do the procedure tomorrow? I've tried calling the helpline and they're closed now.

Is he drinking fluid? He needs to drink drink drink! Clear himself out. If his bowels aren't clear they won't do the procedure. I spent years giving bowel prep to patients and remember all the nagging to drink.

He's had loads to drink. He's had a 2ltr bottle of sugar free lemonade and a huge jug of weak squash.