Bluno Mega 1280 to android app bluetooh connection issues

We were having a problem in connecting the Bluno Mega 1280 to the android app via bluetooth connection. We have tried the demo at this linkmake_clickable_callback(MAGIC_URL_FULL, ' ', 'https://www.dfrobot.com/wiki/index.php/Bluno_SKU:DFR0267#Bluno_Basic_Demo', '', ' class="postlink"') and its able to connect the bluno to the android app provided. However, when we use a different android app from google play like Led Controller, the app doesn't connect to the bluno it says an error 515: not connected to a device. What might be the problem? Is the android app works only depending on the type of microcontroller unit especially on bluno types? Thank in advance.