India Post — cannot track my shipment

Address:

Kolkata, West Bengal, 700094

EX[protected]IN is the tracking number sent to me from SBI. But on Indiapost website, it's showing that consignment details are not available. The message that I got from bank says that they dispatched it on 3/11/18. But till date I am not getting any information. Unless I know when the delivery is expected, it is difficult to be present. Please help.
-Dr. Chandreyee Bhattacharya.