Some big power is telling me something

I found a mistake today.
We had handed out different medicines to our patient five times in a row.
The difference was insulin "cartridge" and "kit."
The patient had injector at home, so we had no doubt when we handed him the cartridge.
But when we look at the prescription carefully, it said "kit".
We didn't realize it until now.

The component is the same so he had no health trouble.
That was good.

We have to be more careful.
When I feel something is wrong, maybe something is happening.
I'll bear it in mind.