Obvious stuff, but be sure of the following:
* Phone or tablet is connected to your home wifi
* Be sure the bridge app is running and listening for a connection
* In B4A, tell it to connect, entering your device's IP address.
I use DHCP reservation in my router for my phone. This way, the IP address never changes. If you are only using the default DHCP without reservation (or a static IP address), then you will have to make sure you are entering the correct address into B4A so it can find your phone. If you don't use DHCP reservation or a static IP address, then you will always have to check the current address assigned to the device before you enter it into B4A.
Hope this helps.