Issue with 'BAPI_ALM_ORDER_MAINTAIN'

Hello Everyone,

I am an SAP ABAP consultant, however my knowledge of SAP Sales and Distribution is very limited.

I am facing a strange issue when I execute the BAPI_ALM_ORDER_MAINTAIN' to create a Service order.

1) I have all the required information to be passed to the BAPI, At first I executed the BAPI (standalone)  via SE37 and passed the required information and The Order was successfully created.

2) Next step: I called the same BAPI programmatically and passed the same information, but i got an error in the return structure " The

           Material did not exist or is not activated.

3)Next Step: I did not pass any material/qty this time programmatically, and the order was successfully executed.

Is there a reason for this disparity?