Runtime Error, Invalid Screen: screen3. Why are showing the message?

Runtime Error, Invalid Screen: screen3. Why are showing the message?

Welcome to the community. The error tells you typed in a wrong screen name… pls post a screanshot of your blocks and also look at the spellings of your screens. Also since this is your first visit to the community have a look at

Check if you have given proper/correct screen name in the blocks used for changing screen