Freestyle Lite test strips not detecting blood

I just got a new batch of Freestyle Lite test strips this morning and have tried 4 or 5 of the strips in the container and none of them seem to detect the presence of my blood (I made sure there was plenty!)

I'm going to try on another batch, but is this likely to be a problem with this particular batch of strips, or with the meter itself? This is the first time it's happened, and the meter was working fine yesterday.

Thanks!

I went back to Tesco's (with a very helpful pharmacist) and he tried strips from a different batch number (using his own blood! ). Looks like a mechanical issue with the strip for that batch. New batch worked fine and he replaced the three defective packs of strips. All good!