Sounds as though you are following a tutorial?
- If the image is too large, that will be an issue.
- Where is the image stored for selection by your App?
Looking at your Screen1 Blocks, there are little errors here and there, which, if you used the ErrorOccured Block properly you would already be aware of.
You are trying to assign a list of AddressesAndNames to local variable 'device' - but it must be initialized as a List first for the data to be processed.
Clock1 Timer is enabled, but the code within the Timer Block is dependant on a 'start value' from Screen2! Note the App will crash if the User opens Screen2 because the Clock Timer is still running (always best to control Clocks via the Blocks).
In Screen2 Blocks you are opening another Screen1 - this allocates more memory for an extra Screen1, which I'm sure is not your intention.
Essentially, Screen2 should be Screen1 and Screen1 should be Screen2 for your code to have a chance of working. However, there isn't really a need for two Screens. All of the GUI and all of the code can be on Screen1 - that is what I recommend you do. Start your Project again, using only Screen1.