HC-O5 can't connect with multiple screens "507"

I have a program for making cocktails. The first time I open the app I can perfectly connect to the Hc-05 but as soon as I change to another screen and I go to lispicker and click on the HC-05 I receive an error message "507". How can I fix this problem.

Use only one screen, see also tip1 here General Tips and Tricks for App Inventor

Alternatively you have to connect again on each screen