Insulin not working?

So i ate a bit more for lunch than i was supposed to. Ok, a lot more. Did a blood test and hit 26 mmol. Ok, nothing to drastic, i'll just inject a correction dose.

Used my normal correction dose, continued on with my day, checking regularly.

It's been an hour now, and my blood sugar has only gone up. now sitting at 31 mmol.

what do

Update: threw out that insulin and grabbed some more from the fridge. Took a dose that is more than my normal correction. Grabbed jelly beans and a new pack of test strips. Ready to weather the storm.