Debasis,
OK, ECC works OK, but that info is irrelevant. As mentioned by expert Abhishek, APO can treat very small values differently than ECC does.
You say you have set the duration of your operation in ECC to .001 minute. I don't know why you selected such a small value, but I will assume there is a legitimate business reason.
What is the base unit of measure in the work center that is associated with this routing?
Best Regards,
DB49