"your device isn't compatible with this version" ... except it is ??? help needed

Hi, I have just created my first app, and I have been testing it locally in my mobile device without any problem. Not just that, I have tested it in another mobile (different brand) and it worked fine too. So, I have build my app, I have uploaded it to Google Play Store and... when we try to download it, we get this message "your device is not compatible with this version". This is how my manifest looks like at the moment: I have also tried changing the "device filter" (from ARMv7 to FAT) and the "Api compatibility" (from Subset to .NET) in the publishing settings, but it doesn´t look to work any better. I would really appreciate the experience of whoever has had this problem before. I have spent quite a good amount of hours banging my head against it, but I can´t find what am I doing wrong. Thanks, R.