1) Ensure that your bundle was created correctly. Follow the steps here.
To check if it is correct, you can search under Product level, Goods > Manage Products > View/Edit Products
Or search under Variant level, Goods > Manage Variants > View/Edit Variants
When you see the ?, it shows that it is a bundle. Hence you are unable to input a value. OneCart will auto-calculate it for you. :)
In this case, you are only able change the quantity by adjusting the quantity for Variant IZNIKC01 instead.