Thanks Nisha and Dharmakasi..It's working fine now..initially I manually added the method into the class.
I have one more question..I need to read the status of the line item from CRM_JEST table and need to check if it set once with status 'I0004' (That item details sent to ECC or not) or not..then I need to disable the material field.
Do I need to directly read the data from tables or in the buffer do we also read CRM_JEST table data.
Thanks,
SaraCRM.