Hi Shiva G,
This really worked. I was doing some small mistakes as you explained above. But the date and time calculation is still incorrect. The exact date time for the ticket mentioned below, should be 4days and 565mins but it is 5days and 874mins. As per our logic as we are taking dates separately so difference between dates when converted to days it is 5 days. But when actually calculating with respect to time it is not completely 5 days. Plz. find the screenshot below.
Looking forward to your help! 
Regards,
Saurabh