India Post — retained for unspecified reason

Address:

Hyderabad, Telangana, 500040

Sir, i have ordered one tamron zoom 95-205mm f6.3 zebra 12 aperture blades for nikon fmount by seller japan-dept on ebay on oct6, 2018 by expedited international post. They have given me the tracking no as en[protected]jp. When i checked about the delivery by using tracking number it is shown as retained by customs for unspecified reason. So i want to know about this when can i expect delivery to my address. How many days it will be retained by customs.in this regard i am enclosing pictures and tracking details by attachments.
Thanking you. D. Sanjeeva ([protected], hyderabad)