Hi Adithya,
Please make sure that at the end of your BLS you are assigning the transaction parameter status = "PASSED" and assign inputXML to outputXML for successful execution. Also please assign the message. Please check those thinks and let me know if any issue.
For your own testing purpose you can also use "Write File" action block within your BLS to write the value within a file and to know the required steps are executed or not.
Thanks
Chandan