Unfortunately, we cannot help you in this case. Even if you are not yet playing in the app, keep the QR codes of weapons. A situation may later occur where you want to play in the app and won't be able to load these weapons into the app without these codes.
The mobile device on which you are playing is connected to the Internet.
You are properly logged into the app with your nickname and password. You can see the login status in the top left corner.
The QR code is perfectly scratched. When it is scanned, the QR code should also be well lit and in focus on the screen.
Be patient. Sometimes you have to move the phone and find the correct distance from the code so that the code is in focus.
If the problems persists, try restarting the app. Otherwise, please let us know at firstname.lastname@example.org and describe your problem (tell us what your nickname is in the game and when you tried to scan the cards).
Tap on your account in the top left corner. Now, you have two options - either let your friend load the QR that appears when you tap the QR icon on the left, or communicate your ID (name-number) to your friend, who enters this ID in the "friends" section.
You can only give the card to friends that you have in the app (See how to add a friend in the app). Then go to your cards in the app, tap on the hero or gun, and display the card. Tap on "send" on the screen with the card, and choose a friend to whom you want to give this card, which will appear in the app for him/her.
Ideally, you should only exchange cards with people whom you know and have as friends in the app. Physically hand the card over to them, and at the same time, send them the same card you have scanned in the app.