Only less people know that there is also train at 21:45 on sunday also slot in vijayawada. IRCTC site won't display in vijayawada to chennai trains list because the train will bypass at perambur railway station. Generally IRCTC will display the trains which are halting at tambaram, Egmore and Chennai central but it won't display the trains which are bypassing at perambur. So change the destination accordingly and book the tickets. As this train reaches vijayawada on sundays the public should come to know this. There is demand for other trains GT, Howrah, Circar, Tamil nadu, Charminar and Bilaspur express