New ketone strips don’t go purple

Hi mums and dads.
I picked up these new ketone urine strips at the pharmacy as they were out of ketostix. However, while they change colour, they don’t go pink or purple. I am wondering if anyone has any idea of where you would place this colour??

talk to the pharmacist. perhaps they are simply a bad batch. are they outdated (despite the fact you just got them)? are those the first few that you used upon opening the vial?