i m just trying to furnish the service tax return for march 2011. But the details of interest on service tax paid due to late deposite of service tax could not be taken. the system asked to verify the source document number and date under 4A(I)(d)i to vii.I have submitting the source document numeber as per as format perscribed by the system as Registration_number_premisescode_st3_mmyyyy. I m trying according to instruction but the system respond that Source document entered by the user not exists in the system. I m facing this problem so that i m not able to submit my return. Please provide me the information regarding the source documents so that i can submit my return.