Make sure you have the right testing strips for your device. There are different versions of agamatrix monitor needing different test strips. If the strips came with the device, it could also happen if it doesn’t fit well in the slot and unable to read the chip. It’s happens to me sometimes and then I try to adjust and insert softly.
I find that happens if my hands are damp and I smush the strip into the blood accidentally so it doesn't absorb correctly. The trick is to dry your hands and put the strip more at 90 degrees on the edge of the blood spot with steady hands. It can be tricky!
When that happens to me it's usually because there is not enough blood on the strip or I've not put it on right (kind of scrape the strip into the blood spot almost straight) x