Error while running a spoon job in java

Hi,

I have developed a job in spoon GUI(PDI-5.4.0.1). The job has only three transformations interconnected with each other.I am getting the following error while running the job through java:
Couldn't find starting point in this job.

Launching a job through spoon always allows me to define the starting point in the launch window but I am unable to set the value through java.

Please help