Hi all, I was wondering if you all can help me out here!

I have been doing the OPK test every morning, yesterday it showed as peek ( flashy smiley face) and that was my last test strip and I opened a new box this morning a new pack and used the new device that came with the new kit. The result this morning came blank face, then I did another test and put the strip in the old device and it said peek! Am a bit confused how two different devices show different results- can someone help to clear the confusion please.