You need to capture both stdout and stderr to see what the .bat file is doing.
Verify that the scheduled task is set to execute program "cmd.exe".
In the arguments field set it to:
/c C:\YourFolderName\YourBatFileName.bat 1>>"C:\YourFolderName\Logs\YourBatFileName-%date:~10,4%-%date:~4,2%%date:~7,2%.log" 2>&1
That will create a daily log file of all executions of the task. The "2>&1" redirects stderr to stdout and ultimately to a single log file.